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Proposed Rule2023-02391

Clean Water Act Methods Update Rule for the Analysis of Effluent

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Published

February 21, 2023

Issuing agencies

Environmental Protection Agency

Abstract

The Environmental Protection Agency (EPA) is proposing changes to its test procedures required to be used by industries and municipalities when analyzing the chemical, physical, and biological properties of wastewater and other samples for reporting under EPA's National Pollutant Discharge Elimination System (NPDES) permit program. The Clean Water Act (CWA) requires EPA to promulgate these test procedures (analytical methods) for analysis of pollutants. EPA anticipates that these proposed changes would provide increased flexibility for the regulated community in meeting monitoring requirements while improving data quality. In addition, this proposed update to the CWA methods would incorporate technological advances in analytical technology and make a series of minor changes and corrections to existing approved methods. As such, EPA expects that there would be no negative economic impacts resulting from these proposed changes.

Full Text

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<title>Federal Register, Volume 88 Issue 34 (Tuesday, February 21, 2023)</title>
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[Federal Register Volume 88, Number 34 (Tuesday, February 21, 2023)]
[Proposed Rules]
[Pages 10724-10771]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-02391]

[[Page 10723]]

Vol. 88

Tuesday,

No. 34

February 21, 2023

Part III

Environmental Protection Agency

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40 CFR Part 136

Clean Water Act Methods Update Rule for the Analysis of Effluent;
Proposed Rule

Federal Register / Vol. 88, No. 34 / Tuesday, February 21, 2023 /
Proposed Rules

[[Page 10724]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 136

[EPA-HQ-OW-2022-0901; FRL-9346-01-OW]
RIN 2040-AG25

Clean Water Act Methods Update Rule for the Analysis of Effluent

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing changes
to its test procedures required to be used by industries and
municipalities when analyzing the chemical, physical, and biological
properties of wastewater and other samples for reporting under EPA's
National Pollutant Discharge Elimination System (NPDES) permit program.
The Clean Water Act (CWA) requires EPA to promulgate these test
procedures (analytical methods) for analysis of pollutants. EPA
anticipates that these proposed changes would provide increased
flexibility for the regulated community in meeting monitoring
requirements while improving data quality. In addition, this proposed
update to the CWA methods would incorporate technological advances in
analytical technology and make a series of minor changes and
corrections to existing approved methods. As such, EPA expects that
there would be no negative economic impacts resulting from these
proposed changes.

DATES: Comments on this proposed rule must be received on or before
April 24, 2023.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OW-2022-0901 by any of the following methods:
<bullet> Federal eRulemaking Portal: <a href="https://www.regulations.gov">https://www.regulations.gov</a>
(our preferred method). Follow the online instructions for submitting
comments.
<bullet> Email: <a href="/cdn-cgi/l/email-protection#afe0f882ebc0ccc4cadbefcadfce81c8c0d9">[email&#160;protected]</a>. Include Docket ID No. EPA-HQ-OW-
2022-0901 in the subject line of the message.
<bullet> Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Office of Water Docket, Mail Code 28221T, 1200 Pennsylvania
Avenue NW, Washington, DC 20460.
<bullet> Hand Delivery or Courier: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operations are 8:30 a.m.-4:30 p.m.,
Monday-Friday (except Federal Holidays).
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Tracy Bone, Engineering and Analysis
Division (4303T), Office of Water, Environmental Protection Agency,
1200 Pennsylvania Avenue NW, Washington, DC 20460-0001; telephone
number: 202-564-5257; email address: <a href="/cdn-cgi/l/email-protection#10527f7e753e6462717369507560713e777f66">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Public Participation
II. General Information
III. Background
IV. Incorporation by Reference
V. Statutory and Executive order Reviews

I. Public Participation

A. Written Comments

Submit your comments, identified by Docket ID No. EPA-HQ-OW-2022-
0901, at <a href="https://www.regulations.gov">https://www.regulations.gov</a> (our preferred method), or the
other methods identified in the ADDRESSES section. Once submitted,
comments cannot be edited or removed from the docket. EPA may publish
any comment received to its public docket. Do not submit to EPA's
docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> any information you consider to
be Confidential Business Information (CBI), Proprietary Business
Information (PBI), or other information whose disclosure is restricted
by statute. Multimedia submissions (audio, video, etc.) must be
accompanied by a written comment. The written comment is considered the
official comment and should include discussion of all points you wish
to make. EPA will generally not consider comments or comment contents
located outside of the primary submission (i.e., on the web, cloud, or
other file sharing system). Please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a> for additional submission methods; the full EPA
public comment policy; information about CBI, PBI, or multimedia
submissions; and general guidance on making effective comments.
Publicly available docket materials are available electronically in
<a href="http://www.regulations.gov">www.regulations.gov</a> at the Water Docket in EPA Docket Center, EPA/DC,
EPA West William J. Clinton Building, Room 3334, 1301 Constitution
Avenue NW, Washington, DC. The Public Reading Room is open from 8:30
a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. Any
copyright material can be viewed at the Reading Room, please contact
the EPA Docket Center, public Reading Room. The telephone number for
the Public Reading Room is 202-566-1744, and the telephone number for
the Water Docket is 202-566-2426. Fax: 202-566-9744. Email: <a href="/cdn-cgi/l/email-protection#42262d212927366f213731362d2f2730312730342b2127022732236c252d34">[email&#160;protected]</a>.

II. General Information

A. Does this action apply to me?

Entities potentially affected by the requirements of this proposed
action include:

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Category Examples of potentially affected entities
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State, Territorial, and Indian Tribal States authorized to administer the National Pollutant Discharge
Governments. Elimination System (NPDES) permitting program; states,
territories, and tribes providing certification under CWA section
401; state, territorial, and tribal-owned facilities that must
conduct monitoring to comply with NPDES permits.
Industry.................................... Facilities that must conduct monitoring to comply with NPDES
permits; the environmental monitoring industry.
Municipalities.............................. Publicly Owned Treatment Works (POTWs) or other municipality-owned
facilities that must conduct monitoring to comply with NPDES
permits.
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This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by this
action. This table lists types of entities that EPA is now aware of
that could potentially be affected by this action. Other types of
entities not listed in the table could also be affected. To determine
whether your facility is affected by this action, you should carefully
examine the applicability language at 40 CFR 122.1 (NPDES purpose and
scope), 40 CFR 136.1 (NPDES permits and CWA) and 40 CFR 403.1
(pretreatment standards purpose

[[Page 10725]]

and applicability). If you have questions regarding the applicability
of this action to a particular entity, consult the appropriate person
listed in the preceding FOR FURTHER INFORMATION CONTACT section.

B. What action is the Agency taking?

Periodically, EPA proposes to update the approved methods in 40 CFR
part 136. In general, the changes proposed in this action fall into the
following categories. The first category is updated versions of EPA
methods currently approved in 40 CFR part 136. The second category is
new or revised methods published by a voluntary consensus standard body
(VCSB) or the United States Geologic Survey (USGS) that are similar to
methods previously adopted as EPA-approved methods in 40 CFR part 136.
The third category is methods EPA has reviewed under the agency's
national Alternate Test Procedure (ATP) program and preliminarily
concluded are appropriate for nationwide use. Finally, EPA is proposing
certain corrections or amendments to the text and tables of 40 CFR part
136. EPA is proposing adoption of these revisions to improve data
quality, update methods to keep current with technology advances, and
provide the regulated community with greater flexibility. The following
paragraphs provide details on the proposed revisions.

C. What is the agency's authority for taking this action?

EPA is proposing this regulation under the authorities of sections
301(a), 304(h), and 501(a) of the CWA; 33 U.S.C. 1251, 1311(a), 1314(h)
and 1361(a). Section 301(a) of the CWA prohibits the discharge of any
pollutant into navigable waters unless the discharge complies with,
among other provisions, an NPDES permit issued under section 402 of the
CWA. Section 304(h) of the CWA requires EPA Administrator to ``. . .
promulgate guidelines establishing test procedures for the analysis of
pollutants that shall include the factors which must be provided in any
certification pursuant to [section 401 of the CWA] or permit
application pursuant to [section 402 of the CWA].'' Section 501(a) of
the CWA authorizes the Administrator to ``. . . prescribe such
regulations as are necessary to carry out this function under [the
CWA].'' EPA generally has codified its test procedure regulations
(including analysis and sampling requirements) for CWA programs at 40
CFR part 136, though some requirements are codified in other parts
(e.g., 40 CFR Chapter I, Subchapters N and O).

III. Background

This preamble describes the abbreviations and acronyms; reasons for
the proposed rule; and a summary of the proposed changes and
clarifications; the legal authority for the proposed rule; methods
incorporated by reference; a summary of the proposed changes and
clarifications and solicits comment from the public.

Abbreviations and Acronyms Used in the Preamble and Proposed Rule Text

ADMI: American Dye Manufacturers Institute
ASTM: ASTM International \1\
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\1\ Formerly known as the American Society for Testing and
Materials (ASTM).
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ATP: Alternate Test Procedure
BHI: Brain heart infusion
BOD<INF>5</INF>: 5-day Biochemical Oxygen Demand
CATC: Cyanide Amenable to Chlorination
CBI: Confidential Business Information
CFR: Code of Federal Regulations
CIE: Capillary Ion Electrophoresis
CNCl: Cyanogen Chloride
CWA: Clean Water Act
EC-MUG: EC broth with 4-methylumbelliferyl-[beta]-D-glucuronide
EDTA: Ethylenediaminetetraacetic acid
EPA: Environmental Protection Agency
DO: Dissolved Oxygen
GC: Gas Chromatography
GC/MS/MS: Gas Chromatography-Tandem Mass Spectrometry
GC/HRMS: Gas Chromatography-High Resolution Mass Spectrometry
ICP/AES: Inductively Coupled Plasma-Atomic Emission Spectroscopy
MIBK: Methyl Isobutyl Ketone
NED: N-(1-naphthyl)-ethylenediamine dihydrochloride
MF: Membrane Filtration
MgCl<INF>2</INF>: Magnesium Chloride
MPN: Most Probable Number
nm: Nanometer
NPDES: National Pollutant Discharge Elimination System
NTTAA: National Technology Transfer and Advancement Act
QC: Quality Control
STGFAA: Stabilized Temperature Graphite Furnace Atomic Absorption
Spectroscopy
TKN: Total Kjeldahl Nitrogen
TOC: Total Organic Carbon
USGS: United States Geological Survey
VCSB: Voluntary Consensus Standards Body

NPDES permits must include conditions designed to ensure compliance
with the technology-based and water quality-based requirements of the
CWA, including in many cases, restrictions on the quantity of specific
pollutants that can be discharged as well as pollutant measurement and
reporting requirements. Often, entities have a choice in deciding which
approved test procedure they will use for a specific pollutant because
EPA has approved the use of more than one method.\2\
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\2\ NPDES permit regulations also specify that the approved
method needs to be sufficiently sensitive. See 40 CFR 122.21(e)(3).
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The procedures for the analysis of pollutants required by CWA
section 304(h) are a central element of the NPDES permit program.
Examples of where these EPA-approved analytical methods must be used
include the following: (1) applications for NPDES permits, (2) sampling
or other reports required under NPDES permits, (3) other requests for
quantitative or qualitative effluent data under the NPDES regulations,
(4) State CWA 401 certifications, and (5) sampling and analysis
required under EPA's General Pretreatment Regulations for Existing and
New Sources of Pollution, 40 CFR 136.1 and 40 CFR 403.12(b)(5)(v).
Periodically, EPA proposes to update the approved methods in 40 CFR
part 136. In general, the changes proposed in this action fall into the
following categories. The first category is updated versions of EPA
methods currently approved in 40 CFR part 136. The second is new or
revised methods published by the VCSBs or the USGS that are similar to
methods previously adopted as EPA-approved methods in 40 CFR part 136.
The third category is methods EPA has reviewed under the Agency's
national ATP program and preliminarily concluded are appropriate for
nationwide use. Finally, EPA is proposing certain corrections or
amendments to the text and tables of 40 CFR part 136. EPA is proposing
adoption of these revisions to improve data quality, update methods to
keep current with technology advances, and provide the regulated
community with greater flexibility. The following paragraphs provide
details on the proposed revisions.

A. Changes to 40 CFR 136.3 To Include New Versions of Previously
Approved EPA Methods

EPA proposes to approve revised versions of the EPA membrane
filtration methods 1103.2, 1106.2, 1600.1, and 1603.1 found in Tables
IA and IH. These methods were approved from 2002 to 2014. The revisions
include standardizing language between the related methods, updating to
reflect current lab practices and clarifying edits. Copies of these
proposed method updated versions are available in the docket to this
rule.
These methods each describe a membrane filter (MF) procedure for
the detection and enumeration of either enterococci or Escherichia coli
bacteria

[[Page 10726]]

by their growth after incubation on selective media. These methods
provide a direct count of bacteria in water samples based on the
development of colonies on the surface of the membrane filter.
1. E. coli. Method 1103.2 describes a MF procedure for the
detection and enumeration of Escherichia coli bacteria in ambient
(fresh) water and is currently approved in Table IH. This is a two-step
method which requires transferring the membrane filter after incubation
on membrane-Thermotolerant Escherichia coli Agar (mTEC) to a pad
saturated with urea substrate.
2. Enterococci. Method 1106.2 describes a MF procedure for the
detection and enumeration of enterococci bacteria in ambient water and
is currently approved in Table IH. This is a two-step method which
requires transferring the membrane filter after incubation on
membraneEnterococcus (mE) agar to Esculin Iron Agar (EIA) medium.
3. Enterococci. Method 1600.1 describes a MF procedure for the
detection and enumeration of enterococci bacteria in ambient (fresh and
marine) water and wastewater and is currently approved in Tables IA and
IH. This is a single-step method that is a modification of EPA Method
1106.1 (mE-EIA). The membrane filter containing the bacterial cells is
placed on membrane-Enterococcus Indoxyl-[beta]-D-Glucoside Agar (mEI).
4. E. coli. Method 1603.1 describes a MF procedure for the
detection and enumeration of thermotolerant Escherichia coli bacteria
in ambient (fresh) waters and wastewaters using Modified membrane-
Thermotolerant Escherichia coli Agar (modified mTEC) and is currently
approved in Table IA and IH.

B. Changes to 40 CFR 136.3 To Include New Versions of Approved ASTM
Methods

EPA is proposing to approve new versions of ASTM methods previously
approved in 40 CFR part 136. These changes to currently approved ASTM
methods in 40 CFR part 136 include minor clarifications and editorial
changes. As an example, ASTM added text to the appropriate method scope
sections to indicate that the method was developed in accordance with
the ``Decision on Principles for the Development of International
Standards, Guides and Recommendations'' issued by the World Trade
Organization Technical Barriers to Trade (TBT) Committee. None of these
proposed changes will affect the performance of the method. The
following describes the changes to current ASTM methods that EPA
proposes to include in 40 CFR part 136. Each entry contains (in the
following order): the parameter, proposed ASTM method number (the last
two digits in the method number represent the year ASTM published), a
brief description of the analytical technique, and a brief description
of any minor procedural changes (if there are any) in this revision
from the last approved version of the method. Method revisions that are
only formatting in nature will have no description of the changes. The
methods listed below are organized according to the table at 40 CFR
part 136 in the order in which they appear.
EPA proposes the following changes to ASTM methods found in Table
IB, and Table II at 40 CFR part 136:
1. Dissolved Oxygen. D888-18 (A, B, C), Dissolved Oxygen, Winkler,
Electrode, Luminescent-based Sensor. Standard D888-18A measures
dissolved oxygen using the Winkler iodometric titration procedure. The
volume of titrant used is proportional to the concentration of
dissolved oxygen in the sample. Standard D888-18B measures dissolved
oxygen in the sample with an electrochemical probe that produces an
electrical potential which is logarithmically proportional to the
concentration of dissolved oxygen in the sample. Standard D888-18C
measures dissolved oxygen with a luminescence-based sensor probe that
employs frequency domain lifetime-based luminescence quenching and
signal processing. The 2012 versions, D888-12 (A), (B) and (C),
currently are approved in Table IB for determination of dissolved
oxygen.
2. Hydrogen Ion (pH). In D1293-18 (A, B), pH, Electrometric. The
activity of hydrogen ion (H+) in the sample is determined
electrometrically with an ion-selective electrode in comparison to at
least two standard reference buffers and pH is reported as the negative
log of that activity. The 1999 version currently is approved in Table
IB.
3. Metals Series. In D1976-20, Elements in Water by Inductively-
Coupled Plasma Atomic Emission Spectroscopy for determination of
aluminum, antimony, arsenic, beryllium, boron, cadmium, chromium,
cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel,
selenium, silver, thallium, vanadium, and zinc. The sample is acid
digested and analyzed by inductively-coupled plasma atomic emission
spectroscopy (ICP/AES) for the simultaneous or sequential determination
of 29 elements. The changes include changing the initial instrument
calibration from using four standards as the first option to using only
one standard and a calibration blank. The 2012 version of this method,
D1976-12, currently is approved in Table IB for 20 of the 29 elements.
4. Surfactants. In D2330-20, Methylene Blue Active Substances, the
sample is mixed with an acidic aqueous solution of methylene blue
reagent, which forms a blue-colored ion pair with any anionic
surfactants which is subsequently extracted with chloroform and washed
with an acidic solution to remove interferences. The intensity of the
blue color is measured using a photometer at 650 nanometers (nm). The
concentration of methylene blue active substances is determined in
comparison to a standard curve. The 2002 version, D2330-02, currently
is approved in Table IB for determination of surfactants.
5. Residue, filterable and nonfilterable. In D5907-18 (A and B),
Filterable Matter (Total Dissolved Solids) and Nonfilterable Matter
(Total Suspended Solids) under Test Method A, an aliquot of the sample
is filtered through a glass fiber filter and the solids trapped on the
filter are dried at 105 [deg]C and weighed to determine the
nonfilterable material (total suspended solids) by difference. Under
Test Method B, the filtrate from Test Method A, or a separate filtrate,
is evaporated to dryness at 180 [deg]C and the residue weighed to
determine the total dissolved solids. The 2013 version is currently
approved in Table IB.
6. Cyanide--Free. In D7237-18, Free Cyanide, Flow Injection,
followed by Gas Diffusion Amperometry an aliquot of the sample is
introduced into a flow injection analysis instrument, where it mixes
with a phosphate buffer to release hydrogen cyanide which diffuses
through a hydrophobic gas diffusion membrane into an alkaline solution
and is detected amperometrically with a silver electrode. This version
also added new information about sulfide interferences and potential
mitigation strategies that EPA anticipates will improve data quality.
There are no other procedural changes. The 2015 version, D7237-15,
currently is approved in Table IB for determination of free cyanide.
7. Cyanide--Total. In D7284-20, Total Cyanide, Manual Distillation
with MgCl<INF>2</INF> followed by Flow Injection, Gas Diffusion
Amperometry, the sample is distilled with acid and a magnesium chloride
catalyst to release cyanide to a sodium hydroxide solution. An aliquot
of the sodium hydroxide solution is introduced into a flow injection
analysis instrument, where it is acidified, and

[[Page 10727]]

the hydrogen cyanide diffuses through a hydrophobic gas diffusion
membrane into an alkaline solution and is detected amperometrically
with a silver electrode. The 2017 reapproval of D7284-13 currently is
approved in Table IB for determination of total cyanide.
8. Organic Carbon. In D7573-18a\e1\, Total Organic Carbon,
Combustion, the sample is sparged with an inert gas to remove dissolved
inorganic carbon, acidified, and then combusted at high temperature to
convert organic carbon to carbon dioxide. The carbon dioxide is
measured with an infra-red detector. This version also adds data from
an interlaboratory method validation study and new method detection
limit values, but there are no procedural changes. The 2017 reapproval
of D7573-09 currently is approved in Table IB for determination of
total organic carbon (TOC).

C. Changes to 40 CFR 136.3 To Include New Versions of Approved
``Standard Methods'' Methods

EPA is proposing to approve new versions of methods developed by
the Standard Methods Committee that were previously approved in 40 CFR
part 136. Standard Methods has reviewed many of their methods in
preparation for releasing the next edition of ``Standard Methods for
the Examination of Water & Wastewater.'' The newer versions provide
clarifications and make editorial corrections. These edits include
removal of referents to specific brand names and trademarks,
incorporation of footnotes into the text, a reformatting of figures,
tables and reference lists, removal of bibliographical references that
are no longer available, small editorial changes based on current style
guides and changes to scientific publishing standards, and minor
clarifications to procedures based on input from users. For example,
the revisions replace distilled water with reagent water in all
methods. As was the case with the previous methods update rule (86 FR
27226, May 19, 2021), EPA generally proposes to approve and include in
40 CFR part 136 only the most recent version of a method published by
the Standard Methods Committee. EPA is proposing to list only one
version of the method with the year of publication designated by the
last four digits in the method number (e.g., 3111 C-2019). The date
indicates the date of the specific revision to the method. This allows
use of a specific method in any edition of the hard copy publication of
``Standard Methods for the Examination of Water & Wastewater'' that
includes a method with the same method number and year of publication.
The proposed revisions to methods previously approved in 40 CFR
part 136 will not affect the performance of the method. Below is a list
of the methods EPA is proposing to include in 40 CFR part 136. Each
entry contains the proposed Standard Methods number and date, the
parameter, and a brief description of the analytical method. The
methods listed below are organized according to the table at 40 CFR
part 136.
EPA proposes to make the following changes to Tables IA, IB, IC, ID
and IH at 40 CFR part 136 for the following parameters:
1. Color. 2120 B-2021, Visual Comparison Method, is a platinum-
cobalt method of measuring color, the unit of color being that produced
by one mg platinum per liter in the form of the chloroplatinate ion.
The 1:2 ratio of cobalt to platinum resulting from the preparation of
the standard platinum-cobalt solution matches the color of natural
waters. The 2011 editorial revision currently is approved in Table IB
for determination of color. 2120 F-2021, American Dye Manufacturers
Institute (ADMI) Weighted-Ordinate Spectrophotometric Method. In
accordance with the Adams-Nickerson chromatic value formula, this
method calculates single-number color difference values (i.e., uniform
color differences). Values are independent of chroma and hue.
Transmittance of light is measured spectrophotometrically at multiple
wavelengths and converted to a set of abstract numbers, which then are
converted to a single number that indicates color value. This number is
expressed on a scale used by the ADMI. The 2011 editorial revision
currently is approved in Table IB for determination of color.
2. Turbidity. 2130 B-2020, Nephelometric Method is based on a
comparison of the intensity of light scattered by the sample under
defined conditions with the intensity of light scattered by a standard
reference suspension under the same conditions. The higher the
intensity of scattered light, the higher the turbidity. Formazin
polymer is used as the primary standard reference suspension. The 2011
editorial revision currently is approved in Table IB for determination
of turbidity.
3. Acidity. 2310 B-2020, Titration Method measures the hydrogen
ions present in a sample as a result of dissociation or hydrolysis of
solutes that react with additions of standard alkali. Acidity thus
depends on the endpoint pH or indicator used. The construction of a
titration curve by recording a sample's pH after successive small,
measured additions of titrant permits identification of inflection
points and buffering capacity, if any, and allows the acidity to be
determined with respect to any pH of interest. Samples of industrial
wastes, acid mine drainage, or other solutions that contain appreciable
amounts of hydrolyzable metal ions such as iron, aluminum, or manganese
are treated with hydrogen peroxide to ensure the oxidation of any
reduced forms of polyvalent cations and are boiled to hasten
hydrolysis. Acidity results may be highly variable if this procedure is
not followed exactly. The 2011 editorial revision currently is approved
in Table IB for determination of acidity.
4. Alkalinity. 2320 B-2021 Titration Method, measures the hydroxyl
ions present in a sample resulting from dissociation or hydrolysis of
solutes that react with additions of standard acid. Alkalinity thus
depends on the endpoint pH used. For samples of low alkalinity (less
than 20 mg/L CaCO<INF>3</INF>) an extrapolation technique based on the
near proportionality of concentration of hydrogen ions to excess of
titrant beyond the equivalence point is used. The amount of standard
acid required to reduce the pH exactly 0.30 pH unit is measured
carefully. Because this change in pH corresponds to an exact doubling
of the hydrogen ion concentration, a simple extrapolation can be made
to the equivalence point. The 2011 editorial revision currently is
approved in Table IB for determination of alkalinity.
5. Hardness. 2340 B-2021, Hardness by Calculation is the preferred
method for determining hardness by calculating it from the results of
separate determinations of calcium and magnesium by any approved method
provided that the sum of the lowest point of quantitation for Ca and Mg
is below the NPDES permit requirement for hardness. The 2011 editorial
revision currently is approved in Table IB for determination of
hardness. In 2340 C-2021, Ethylenediaminetetraacetic acid (EDTA)
Titrimetric Method, EDTA forms a chelated soluble complex when added to
a solution of certain metal cations. If a small amount of a dye such as
eriochrome black T or calmagite is added to an aqueous solution
containing calcium and magnesium ions at a pH of 10.0 <plus-minus> 0.1,
the color of the solution becomes wine red. If EDTA is added as a
titrant, the calcium and magnesium will be complexed, and when all of
the magnesium and calcium has been complexed, the solution turns from
wine red to blue, marking the endpoint of the titration. The volume of
titrant used is proportional to hardness in the

[[Page 10728]]

sample. Magnesium ion must be present to yield a satisfactory endpoint.
To ensure this, a small amount of complexometrically neutral magnesium
salt of EDTA is added to the buffer; this automatically introduces
sufficient magnesium and obviates the need for a blank correction. The
2011 editorial revision currently is approved in Table IB for
determination of hardness.
6. Specific Conductance. 2510 B-2021 measures conductance (or
resistance) in the laboratory using a standard potassium chloride
solution and from the corresponding conductivity, a cell constant is
calculated. Most conductivity meters do not display the actual solution
conductance, or resistance, rather, they generally have a dial that
permits the user to adjust the internal cell constant to match the
conductivity of a standard. Once the cell constant has been determined,
or set, the conductivity of an unknown solution is displayed by the
meter. The 2011 editorial revision currently is approved in Table IB
for determination of specific conductance.
7. Residue--Total. In 2540 B-2020 an aliquot of a well-mixed sample
is evaporated in a pre-weighed evaporating dish at 103-105 [deg]C to
constant weight in a 103 to 105 [deg]C oven. The increase compared to
the empty pre-weighed dish weight represents total solids. The 2015
version of the method currently is approved in Table IB for
determination of total residue. In 2540 C-2020, Total Dissolved Solids
Dried at 180 [deg]C (Residue--filterable in Table IB) a measured volume
of a well-mixed sample is filtered through a glass fiber filter with
applied vacuum. The entire exposed surface of the filter is washed with
at least 3 successive volumes of reagent-grade water with continued
suction until all traces of water are removed. The total filtrate (with
washings) is then transferred to a pre-weighed dish and evaporated to
dryness. Successive volumes of sample are added to the same dish after
evaporation if necessary to yield between 2.5 and 200 mg of dried
residue. The evaporated residue is then dried for one hour or more in
an oven at 180 [deg]C, cooled in a desiccator to ambient temperature,
and weighed until the weight change is less than 0.5 mg. The 2015
version of the method currently is approved in Table IB for
determination of filterable residue. In 2540 D-2020, Total Suspended
Solids Dried from 103 to 105 [deg]C (Residue--non-filterable total
suspended solids (TSS) in Table IB) a well-mixed sample is filtered
through a pre-weighed standard glass-fiber filter. The filter and the
retained residue are then dried to a constant weight in a 103 to 105
[deg]C oven. The increase in filter weight represents TSS. The 2015
version of the method currently is approved in Table IB for
determination of non-filterable residue. In 2540 E-2020, Fixed and
Volatile Solids Ignited at 550 [deg]C (Residue--volatile in Table IB)
the residue obtained from the determination of total (Method 2540 B),
filterable (Method 2540 C), or non-filterable residue (Method 2540 D)
is ignited at 550 <plus-minus> 50 [deg]C in a muffle furnace, cooled in
a desiccator to ambient temperature and weighed. Repeated successive
cycles of drying, cooling, desiccating, and weighing are performed
until the weight change is less than 0.5 mg. The remaining solids are
fixed total, dissolved, or suspended solids, while those lost to
ignition are volatile total, dissolved, or suspended solids. The 2015
version of the method currently is approved in Table IB for
determination of volatile residue. In 2540 F-2020, Settleable Solids
(aka, Residue--settleable in Table IB), a well-mixed sample is used to
fill an Imhoff cone or graduated cylinder to the 1-L mark. The sample
is allowed to settle for 45 minutes, then gently agitated near the
sides of the cone (or graduated cylinder) with a rod or by spinning.
The sample is then allowed to settle for another 15 minutes and the
volume of settleable solids in the cone (or graduated cylinder) is
recorded as mL/L. When applicable, the recorded volume is corrected for
interference from pockets of liquid volume. The 2015 version of the
method currently is approved in Table IB for determination of
settleable residue.
8. Multiple metals by flame atomic absorption spectrometry.
a. 3111 B-2019, Direct Air-Acetylene Flame Method. The 2011
editorial revision currently is approved in Table IB for determination
of antimony, cadmium, calcium, chromium, cobalt, copper, gold, iridium,
iron, lead, magnesium, manganese, nickel, palladium, platinum,
potassium, rhodium, ruthenium, silver, sodium, thallium, tin, and zinc.
A sample is aspirated into a flame and the metals are atomized. A light
beam is directed through the flame, into a monochromator, and onto a
detector that measures the amount of light absorbed by the atomized
metal in the flame. Because each metal has its own characteristic
absorption wavelength, a source lamp composed of that element is used.
The amount of energy at the characteristic wavelength absorbed in the
flame is proportional to the concentration of the element in the sample
over a limited concentration range.
b. 3111 C-2019, Extraction and Air-Acetylene Flame Method consists
of chelation with ammonium pyrrolidine dithiocarbamate (APDC) and
extraction into methyl isobutyl ketone (MIBK), followed by aspiration
into an air-acetylene flame and is suitable for the determination of
low concentrations of cadmium, chromium, cobalt, copper, iron, lead,
manganese, nickel, silver, and zinc. The 2011 editorial revision
currently is approved in Table IB for determination of cadmium,
chromium, cobalt, copper, iron, lead, nickel, silver, and zinc.
EPA proposes to approve method 3111 C for manganese. This parameter
was inadvertently left off in an earlier rulemaking approving method
3111 C.
c. 3111 D-2019, Direct Nitrous Oxide-Acetylene Flame Method. A
sample is aspirated into a flame produced using a mixture of nitrous
oxide and acetylene and the metals are atomized. A light beam is
directed through the flame, into a monochromator, and onto a detector
that measures the amount of light absorbed by the atomized metal in the
flame. The 2011 editorial revision currently is approved in Table IB
for determination of aluminum, barium, beryllium, molybdenum, osmium,
titanium, and vanadium. In addition, EPA proposes to approve method
3111 D for calcium. This parameter was inadvertently left off in an
earlier rulemaking approving method 3111 D.
d. 3111 E-2019, Extraction and Nitrous Oxide-Acetylene Flame
Method. The method consists of chelation with 8-hydroxyquinoline,
extraction with MIBK, and aspiration into a nitrous oxide-acetylene
flame and is suitable for the determination of aluminum at
concentrations less than 900 [mu]g/L and beryllium at concentrations
less than 30 [mu]g/L. The 2011 editorial revision currently is approved
in Table IB for determination of aluminum, and beryllium.
9. Mercury--Total. 3112 B-2020, Metals by Cold-Vapor Atomic
Absorption Spectrometric Method is a flameless AA procedure based on
the absorption of radiation at 253.7 nm by mercury vapor. The mercury
in a sample is reduced to the elemental state and aerated from solution
in a closed system. The mercury vapor passes through a cell positioned
in the light path of an atomic absorption spectrophotometer. Absorbance
is measured as a function of mercury concentration. The 2011 editorial
revision currently is approved in Table IB for determination of
mercury.

[[Page 10729]]

10. Metals by AA Furnace. In 3113 B-2020, Electrothermal Atomic
Absorption Spectrometric Method, a discrete sample volume is dispensed
into the graphite sample tube (or cup). Typically, determinations are
made by heating the sample in three or more stages. First, a low
current heats the tube to dry the sample. The second, or charring,
stage destroys organic matter and volatilizes other matrix components
at an intermediate temperature. Finally, a high current heats the tube
to incandescence and, in an inert atmosphere, atomizes the element
being determined. Additional stages frequently are added to aid in
drying and charring, and to clean and cool the tube between samples.
The resultant ground-state atomic vapor absorbs monochromatic radiation
from the source. A photoelectric detector measures the intensity of
transmitted radiation. The inverse of the transmittance is related
logarithmically to the absorbance, which is directly proportional to
the number density of vaporized ground-state atoms (the Beer-Lambert
law) over a limited concentration range. The 2010 version of the method
currently is approved in Table IB for determination of aluminum,
antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt,
copper, iron, lead, manganese, molybdenum, nickel, selenium, silver,
and tin. Although not specifically listed as target analytes in 3113 B,
the 2010 version of the method is also approved in Table IB for
determination of gold, thallium, and vanadium, as these elements may
also be determined using the method.
11. Arsenic and Selenium by AA Gaseous Hydride. 3114 B-2020, Manual
Hydride Generation/Atomic Absorption Spectrometric Method is a manual
hydride generation method that is applicable to the determination of
arsenic and selenium by conversion to their hydrides by sodium
borohydride reagent and transport into an atomic absorption atomizer.
The 2011 editorial revision currently is approved in Table IB for
determination of arsenic and selenium. 3114 C-2020, Continuous Hydride
Generation/Atomic Absorption Spectrometric Method is a continuous-flow
hydride generation method that is applicable to the determination of
arsenic and selenium by conversion to their hydrides by sodium
borohydride reagent and transport into an atomic absorption atomizer.
The continuous hydride generator offers the advantages of simplicity in
operation, excellent reproducibility, low detection limits, and high
sample volume throughput for selenium analysis following preparations
as described in 3500-Se B or 3114 B.4c and d. The 2011 editorial
revision currently is approved in Table IB for determination of arsenic
and selenium.
12. Multiple Metals by ICP/AES (Plasma Emission Spectroscopy). In
3120 B-2020, an Inductively Coupled Plasma (ICP) source consists of a
flowing stream of argon gas ionized by an applied radio frequency field
typically oscillating at 27.1 MHz. This field is inductively coupled to
the ionized gas by a water-cooled coil surrounding a quartz torch that
supports and confines the plasma. A sample aerosol is generated in an
appropriate nebulizer and spray chamber and is carried into the plasma
through an injector tube located within the torch. The sample aerosol
is injected directly into the ICP, subjecting the constituent atoms to
temperatures of about 6000 to 8000 [deg]K. Because this results in
almost complete dissociation of molecules, significant reduction in
chemical interferences is achieved. The high temperature of the plasma
excites atomic emission efficiently. Ionization of a high percentage of
atoms produces ionic emission spectra. The ICP provides an optically
thin source that is not subject to self-absorption except at very high
concentrations. Total metals are determined after appropriate
digestion. The 2011 editorial revision currently is approved in Table
IB for determination of aluminum, antimony, arsenic, barium, beryllium,
boron, cadmium, calcium, chromium, cobalt, copper, iron, lead,
magnesium, manganese, molybdenum, nickel, potassium, selenium, silica,
silver, sodium, thallium, vanadium, and zinc. Although not specifically
listed as a target analyte in method 3120 B, the 2011 version of the
method is also approved in Table IB for determination of phosphorus
because this element may also be determined using the method.
13. Multiple Metals by Inductively Coupled Plasma-Mass
Spectrometry. In this method, 3125 B-2020, Inductively Coupled Plasma-
Mass Spectrometry (ICP-MS) Method, a sample is introduced into an
argon-based, high-temperature radio-frequency plasma, usually via
pneumatic nebulization. As energy transfers from the plasma to the
sample stream, the target element desolvation, atomization, and
ionization. The resulting ions are extracted from the plasma through a
differential vacuum interface and separated based on their mass-to-
charge (m/z) ratio by a mass spectrometer. Typically, either a
quadrupole (with or without collision cell technology or dynamic
reaction cell) or magnetic sector (high-resolution) mass spectrometer
is used. An electron multiplier detector counts the separated ions, and
a computer-based data-management system processes the resulting
information. The 2011 editorial revision currently is approved in Table
IB for determination of aluminum, antimony, arsenic, barium, beryllium,
cadmium, chromium, cobalt, copper, lead, manganese, molybdenum, nickel,
potassium, selenium, silver, thallium, vanadium, and zinc. Although not
specifically listed as a target analyte in method 3125 B, the 2011
version of the method is also approved in Table IB for determination of
boron, calcium, gold, iridium, iron, magnesium, palladium, platinum,
potassium, rhodium, ruthenium, silica, sodium, tin, and titanium as
these elements may also be determined using the method.
14. 3500 Colorimetric Series for Multiple Metals.
a. Aluminum. In 3500-Al B-2020, Eriochrome Cyanine R Method with
Eriochrome cyanine R dye, dilute aluminum solutions buffered to a pH of
6.0 produce a red to pink complex that exhibits maximum absorption at
535 nm. The intensity of the developed color is influenced by the
aluminum concentration, reaction time, temperature, pH, alkalinity, and
concentration of other ions in the sample. To compensate for color and
turbidity, the aluminum in one portion of a sample is complexed with
EDTA to provide a blank. The interference of iron and manganese, two
elements commonly found in water when aluminum is present, is
eliminated by adding ascorbic acid. The 2011 editorial revision
currently is approved in Table IB for determination of aluminum.
b. Arsenic. In 3500-As B-2020, Silver Diethyldithiocarbamate
Method, arsenite, containing trivalent arsenic, is reduced selectively
by aqueous sodium borohydride solution to arsine, AsH<INF>3</INF>, in
an aqueous medium of pH 6. Arsenate, methylarsonic acid, and
dimethylarsinic acid are not reduced under these conditions. The
generated arsine is swept by a stream of oxygen-free nitrogen from the
reduction vessel through a scrubber containing glass wool or cotton
impregnated with lead acetate solution into an absorber tube containing
silver diethyldithiocarbamate and morpholine dissolved in chloroform.
The intensity of the red color that develops is measured at 520 nm. The
2011 editorial revision currently is approved in Table IB for
determination of arsenic.
c. Calcium. In 3500-Ca B-2020, EDTA Titrimetric Method, EDTA is
added to water containing both calcium and

[[Page 10730]]

magnesium, where it combines first with the calcium. Calcium can be
determined directly, with EDTA, when the pH is made sufficiently high
that the magnesium is largely precipitated as the hydroxide and an
indicator is used that combines with calcium only. Several indicators
give a color change when all the calcium has been complexed by the EDTA
at a pH of 12 to 13. The 2011 editorial revision currently is approved
in Table IB for determination calcium.
d. Chromium. 3500-Cr B-2020, Colorimetric Method. This procedure
measures only hexavalent chromium, (chromium VI). The hexavalent
chromium is determined colorimetrically by reaction with
diphenylcarbazide in acid solution. A red-violet colored complex of
unknown composition is produced. The 2011 editorial revision currently
is approved in Table IB for determination of dissolved hexavalent
chromium (chromium VI). 3500-Cr C-2020, Ion Chromatographic Method.
This method is applicable to determination of dissolved hexavalent
chromium in drinking water, groundwater, and industrial wastewater
effluents. An aqueous sample is filtered, and its pH adjusted to
between 9 and 9.5 with a concentrated buffer. This pH adjustment
reduces the solubility of trivalent chromium and preserves the
hexavalent chromium oxidation state. The sample is introduced into the
instrument's eluent stream of ammonium sulfate and ammonium hydroxide.
Trivalent chromium in solution is separated from the hexavalent
chromium by the column. After separation, hexavalent chromium reacts
with an azide dye to produce a chromogen that is measured at 530 or 540
nm. Hexavalent chromium is identified based on retention time. The 2011
editorial revision currently is approved in Table IB for determination
of dissolved hexavalent chromium (chromium VI).
e. Copper Colorimetric. In 3500-Cu B-2020, Neocuproine Method, the
sample is treated with hydroxylamine hydrochloride to reduce any cupric
ions (Cu\2+\) to cuprous ions (Cu\+\). Sodium citrate is used to
complex metallic ions that might precipitate when the pH is raised. The
pH is adjusted to between 4 and 6 with ammonium hydroxide
(NH<INF>4</INF>OH), a solution of neocuproine (2,9-dimethyl-1,10-
phenanthroline) in methanol is added, and the resultant complex is
extracted into chloroform (CHCl<INF>3</INF>). After dilution of the
CHCl<INF>3</INF> to an exact volume with methanol (CH<INF>3</INF>OH),
the absorbance of the solution is measured at 457 nm. The 2011
editorial revision currently is approved in Table IB for determination
of copper. In 3500-Cu C-2020, Bathocuproine Method, cuprous ion forms a
water-soluble orange-colored chelate with disodium bathocuproine
disulfonate (sodium 4,4'-(2,9-dimethyl-1,10-phenanthroline-4,7-
diyl)dibenzenesulfonate). While the color forms over the pH range 3.5
to 11.0, the recommended pH range is between 4 and 5. The sample is
buffered at a pH of about 4.3 and reduced with hydroxylamine
hydrochloride. The absorbance is measured at 484 nm. The 2011 editorial
revision currently is approved in Table IB for determination of copper.
f. Potassium. In 3500-K B-2020, Flame Photometric Method, trace
amounts of potassium can be determined in either a direct-reading or
internal-standard type of flame photometer at a wavelength of 766.5 nm.
The 2011 editorial revision currently is approved in Table IB for
determination of potassium. In 3500-K C-2020, Potassium-Selective
Electrode Method, potassium ions are measured potentiometrically by
using a potassium ion-selective electrode and a double-junction,
sleeve-type reference electrode. The analysis is performed with either
a pH meter having an expanded millivolt scale capable of being read to
the nearest 0.1 mV or a specific-ion meter having a direct
concentration scale for potassium. Before measurement, an ionic
strength adjustor reagent is added to both standards and samples to
maintain a constant ionic strength. The electrode response is measured
in standard solutions with potassium concentrations spanning the range
of interest using a calibration line derived either by the instrument
meter or manually. The electrode response in sample solutions is
measured following the same procedure and potassium concentration
determined from the calibration line or instrument direct readout. The
2011 editorial revision currently is approved in Table IB for
determination of potassium.
g. Manganese. In 3500-Mn B-2020, Persulfate Method, persulfate
oxidation of soluble manganous compounds to form permanganate is
carried out in the presence of silver nitrate. The resulting color is
stable for at least 24 hours if excess persulfate is present and
organic matter is absent. The 2011 editorial revision currently is
approved in Table IB for determination of manganese.
h. Sodium. In 3500-Na B-2020, Flame Emission Photometric Method a
sample is nebulized into a gas flame under carefully controlled,
reproducible excitation conditions. The sodium resonant spectral line
at 589 nm is isolated by interference filters or by light-dispersing
devices such as prisms or gratings. Emission light intensity is
measured by a phototube, photomultiplier, or photodiode. The light
intensity at 589 nm is approximately proportional to the sodium
concentration. The 2011 editorial revision currently is approved in
Table IB for determination of sodium.
i. Lead. In 3500-Pb B-2020, Dithizone Method, an acidified sample
containing microgram quantities of lead is mixed with ammoniacal
citrate-cyanide reducing solution and extracted with dithizone in
chloroform (CHCl<INF>3</INF>) to form a cherry-red lead dithizonate.
The color of the mixed color solution is measured photometrically. The
2011 editorial revision currently is approved in Table IB for
determination of lead.
j. Zinc. 3500-Zn B-2020, Zincon Method. Zinc forms a blue complex
with zincon (2-carboxy-2'-hydroxy-5'-sulfoformazyl benzene) in a
solution buffered to pH 9.0. Other heavy metals likewise form colored
complexes with zincon. Cyanide is added to complex zinc and heavy
metals. Cyclohexanone is added to selectively free zinc from its
cyanide complex so that it can be complexed with zincon to form a blue
color which is measured spectrophotometrically at 620 nm. Sodium
ascorbate reduces manganese interference. The developed color is stable
except in the presence of copper. The 2011 editorial revision currently
is approved in Table IB for determination of zinc.
15. 4110 Series, Ion Chromatography.
a. In 4110 B-2020, Ion Chromatography with Chemical Suppression of
Eluent Conductivity, is approved in Table IB for determination of
bromide, chloride, fluoride, nitrate, nitrite, orthophosphate, and
sulfate. A water sample is injected into a stream of eluent and passed
through a series of ion exchangers. The anions of interest are
separated based on their relative affinities for a low-capacity,
strongly basic anion exchanger (guard and analytical columns). The
separated anions are directed through a suppressor device that provides
continuous suppression of eluent conductivity and enhances analyte
response. In the suppressor, the separated anions are converted to
their highly conductive acid forms while the conductivity of the eluent
is greatly decreased. The separated anions in their acid forms are
measured by conductivity. They are identified based on retention time
as compared to standards. Quantitation is by measurement of peak area
or peak height. The 2011 editorial revision

[[Page 10731]]

currently is approved in Table IB for determination of bromide,
chloride, fluoride, nitrate, combined nitrate-nitrite, nitrite,
orthophosphate, and sulfate.
b. 4110 C-2020, Single-Column Ion Chromatography with Direct
Conductivity Detection. An aqueous sample is injected into an ion
chromatograph consisting of an injector port, analytical column, and
conductivity detector. The sample merges with the eluent stream and is
pumped through the analytical column where the anions are separated
based on their affinity for the active sites of the column packing
material. Concentrations are determined by direct conductivity
detection without chemical suppression. The 2011 editorial revision
currently is approved in Table IB for determination of bromide,
chloride, fluoride, nitrate, combined nitrate-nitrite, nitrite,
orthophosphate, and sulfate.
c. 4110 D-2020, Ion Chromatographic Determination of Oxyhalides and
Bromide. The sample is analyzed in a manner similar to that in 4110 B-
2020. However, bromate has been shown to be subject to positive
interferences in some matrices. The interference is noticeable usually
as a flattened peak. It often can be eliminated by passing the sample
through an H\+\ off-line solid-phase extraction (SPE) cartridge, by
selection of a different column-eluent combination, or by diluting the
eluent, which will increase retention times and spread the
chromatogram. Additionally, chloride or a nontarget analyte present in
unusually high concentration may overlap with a target analyte
sufficiently to cause problems in quantitation or may cause retention-
time shifts. Dilution of the sample may resolve this problem. The 2011
editorial revision currently is approved in Table IB for determination
of bromide.
16. Inorganic Anions by CIE/UV (Capillary Ion Electrophoresis). In
4140 B-2020, Capillary Ion Electrophoresis with Indirect UV Detection,
the sample is introduced at the cathodic end of the capillary and
anions are separated based on their differences in mobility in the
electric field as they migrate through the capillary. Cations migrate
in the opposite direction and are not detected. Water and neutral
organics are not attracted toward the anode. They migrate after the
anions and thus do not interfere with anion analysis. Anions are
detected as they displace charge-for-charge the UV-absorbing
electrolyte anion (chromate), causing a net decrease in UV absorbance
in the analyte anion zone compared to the background electrolyte.
Detector polarity is reversed to provide positive millivolt response to
the data system. As in chromatography, the analytes are identified by
their migration time and quantitated by using time-corrected peak area
relative to standards. The 2011 editorial revision currently is
approved in Table IB for determination of bromide, chloride, fluoride,
nitrate, combined nitrate-nitrite, nitrite, orthophosphate, and
sulfate.
17. 4500 Series, Chloride.
a. 4500-Cl- B-2021, Titrimetric Method. In a neutral or
slightly alkaline solution, potassium chromate can indicate the
endpoint of the silver nitrate titration of chloride. Silver chloride
is precipitated quantitatively before red silver chromate is formed. In
this version of the method approved by the Standard Methods Committee
in 2021, additional information regarding removal of interferences
caused by sulfide, thiosulfate, and sulfite ions by digestion of the
sample with hydrogen peroxide prior to titration has been added to the
sample preparation procedures. A tighter pH range of 8-10, as opposed
to 7-10, is specified for adjustment of the pH of the sample prior to
titration. A reference has been added for the 2021 Standard Methods
Joint Task Group validation report titled: ``Interlaboratory validation
study for the use of H<INF>2</INF>O<INF>2</INF> with boiling for
determining Cl-.'' The 2011 editorial revision currently is
approved in Table IB for determination of chloride.
b. 4500-Cl- C-2021, Mercuric Nitrate Method. Chloride
can be titrated with mercuric nitrate, Hg(NO<INF>3</INF>)<INF>2</INF>,
because of the formation of soluble, slightly dissociated mercuric
chloride. In the pH range 2.3 to 2.8, diphenylcarbazone indicates the
titration endpoint by formation of a purple complex with the excess
mercuric ions. Xylene cyanol FF serves as a pH indicator and endpoint
enhancer. Increasing the strength of the titrant and modifying the
indicator mixtures extend the range of measurable chloride
concentrations. The 2011 editorial revision currently is approved in
Table IB for determination of chloride.
c. 4500-Cl- D-2021, Potentiometric Method. Chloride is
determined by potentiometric titration with silver nitrate solution
with a glass and silver-silver chloride electrode system. During
titration, an electronic voltmeter is used to detect the change in
potential between the two electrodes. The endpoint of the titration is
that instrument reading at which the greatest change in voltage has
occurred for a small and constant increment of silver nitrate added.
The 2011 editorial revision currently is approved in Table IB for
determination of chloride.
d. 4500-Cl- E-2021, Automated Ferricyanide Method.
Thiocyanate ion is liberated from mercuric thiocyanate by the formation
of soluble mercuric chloride. In the presence of ferric ion, free
thiocyanate ion forms a highly colored ferric thiocyanate, of which the
intensity is proportional to the chloride concentration. The 2011
editorial revision currently is approved in Table IB for determination
of chloride.
18. 4500 Series Cyanide Total or Available.
a. 4500-CN- B-2021, Manual Distillation (as Preliminary
Treatment of Samples). Total cyanides are measured after preliminary
treatment of samples for preservation and to remove interferences. The
preliminary treatment required depends on which interfering substances
the samples contain. Distillation removes many interfering substances,
but other pretreatment procedures will be needed for sample containing
sulfides, fatty acids, oxidizing agents, nitrites, and nitrates. The
2016 version of the method currently is approved in Table IB for
preliminary treatment of samples to be used for determination of
cyanide.
b. 4500-CN- C-2021, Total Cyanide after Distillation.
Hydrogen cyanide (HCN) is liberated from an acidified sample by
distillation and purging with air, with the HCN gas collected in a NaOH
scrubbing solution. The cyanide concentration in the scrubbing solution
is determined via titrimetric, colorimetric, or potentiometric
procedures. The 2016 version of the method currently is approved in
Table IB for preliminary treatment of samples to be used for
determination of cyanide.
c. 4500-CN- D-2021, Titrimetric Method. CN-
in the alkaline distillate from the preliminary treatment procedures
(4500-CN- B and C) is titrated with standard silver nitrate
(AgNO<INF>3</INF>) to form the soluble cyanide complex
Ag(CN)<INF>2</INF>-. As soon as all CN- has been
complexed and a small excess of Ag\+\ has been added, the silver-
sensitive indicator, p-dimethylaminobenzalrhodanine, detects the excess
Ag\+\ and immediately changes color from yellow to salmon. The 2016
version of the method currently is approved in Table IB for
determination of cyanide.
d. 4500-CN- E-2021, Spectrophotometric Method. Total
CN- in the alkaline distillate from the preliminary
treatment procedures (4500-CN- B and C) is converted to
cyanogen chloride (CNCl) by reaction with chloramine-T at pH <8 without
hydrolyzing to cyanate (CNO-). After

[[Page 10732]]

the reaction is complete, adding a pyridine-barbituric acid reagent
turns CNCl a red-blue color. Maximum color absorbance in aqueous
solution is between 575 and 582 nm. The 2016 version of the method
currently is approved in Table IB for determination of cyanide.
e. 4500-CN- F-2021, Ion Selective Electrode Method.
Total CN- in the alkaline distillate from the preliminary
treatment procedures (4500-CN- B and C) is determined
potentiometrically by using a CN--ion selective electrode.
The 2016 version of the method currently is approved in Table IB for
determination of cyanide.
f. 4500-CN- G-2021, Cyanides Amenable to Chlorination
after Distillation. Available cyanide, or cyanide amenable to
chlorination (CATC), can be determined when a portion of the sample is
chlorinated at high pH and cyanide levels in the chlorinated sample are
determined after manual distillation followed by titrimetric or
spectrophotometric measurement. CATC is calculated by the difference
between the results for cyanide in the unchlorinated sample and the
results for the chlorinated sample. The 2016 version of the method
currently is approved in Table IB for preliminary treatment of samples
to be used for determination of available cyanide.
g. 4500-CN- N-2021, Total Cyanide after Distillation by
Flow Injection Analysis. Total cyanides are digested and steam-
distilled from the sample (4500-CN- C), The cyanide in this
distillate is converted to CNCl by reaction with chloramine-T at pH <8.
The CNCl then forms a red-blue dye by reacting with pyridine-barbituric
acid reagent. The absorbance of this red dye is measured at 570 nm and
is proportional to the total or weak acid dissociable cyanide in the
sample. The 2016 version of the method currently is approved in Table
IB for determination of cyanide.
19. 4500 Total Fluoride Series.
a. 4500-F- B-2021, Preliminary Distillation Step.
Fluoride is separated from other nonvolatile constituents in water by
conversion to hydrofluoric or fluosilicic acid and subsequent
distillation. The conversion is accomplished by using a strong, high-
boiling acid. To protect against glassware etching, hydrofluoric acid
is converted to fluosilicic acid by using soft glass beads.
Quantitative fluoride recovery is accomplished by using a relatively
large sample. Acid and sulfate carryover are minimized by distilling
over a controlled temperature range. The 2011 editorial revision
currently is approved in Table IB for preliminary treatment of samples
to be used for determination of fluoride.
b. 4500-F- C-2021, Ion-Selective Electrode Method. The
fluoride electrode is an ion-selective sensor that measures the ion
activity of fluoride in solution rather than concentration. The key
element in the fluoride electrode is the laser-type doped lanthanum
fluoride crystal across which a potential is established by fluoride
solutions of different concentrations. The crystal contacts the sample
solution at one face and an internal reference solution at the other.
Fluoride ion activity depends on the solution total ionic strength and
pH, and on fluoride complexing species. Adding an appropriate buffer
provides a nearly uniform ionic strength background, adjusts pH, and
breaks up complexes. In effect, the electrode measures concentration.
The 2011 editorial revision currently is approved in Table IB for
determination of fluoride.
c. 4500-F- D-2021, SPADNS Method. The SPADNS
colorimetric method is based on the reaction between fluoride and a
``lake'' of zirconium-dye. Fluoride reacts with the dye lake,
dissociating a portion of it into a colorless complex anion
(ZrF<INF>6</INF>2-) and the dye. As the amount of fluoride
increases, the color produced becomes progressively lighter and
absorbance is measured colorimetrically at 570 nm. The 2011 editorial
revision currently is approved in Table IB for determination of
fluoride.
d. 4500-F- E-2021, Complexone Method. The sample is
distilled in the automated system, and the distillate is reacted with
alizarin fluorine blue-lanthanum reagent to form a blue complex that is
measured colorimetrically at 620 nm. The 2011 editorial revision
currently is approved in Table IB for determination of fluoride.
20. 4500 Hydrogen ion (pH). 4500-H\+\ B-2021, Electrometric Method.
The basic principle of electrometric pH measurement is determination of
the activity of the hydrogen ions by potentiometric measurement using a
standard hydrogen electrode and a reference electrode. The hydrogen
electrode consists of a platinum electrode across which hydrogen gas is
bubbled at a pressure of 101 kilopascal. Because of difficulty in its
use and the potential for poisoning the hydrogen electrode, the glass
electrode commonly is used. The electromotive force (emf) produced in
the glass electrode system varies linearly with pH. This linear
relationship is described by plotting the measured emf against the pH
of different buffers. A sample's pH is determined by extrapolation.
This version of the method adds information to Section 2--Apparatus,
regarding equipment that may be used for manual or automatic
temperature compensation. The 2011 editorial revision currently is
approved in Table IB for determination of pH.
21. 4500 Kjeldahl Nitrogen (TKN) Series.
a. 4500-Norg B-2021, Macro-Kjeldahl Method. In the presence of
sulfuric acid (H<INF>2</INF>SO<INF>4</INF>), potassium sulfate
(K<INF>2</INF>SO<INF>4</INF>), and a cupric sulfate (CuSO<INF>4</INF>)
catalyst, amino nitrogen of many organic materials is converted to
ammonium. Free ammonia also is converted to ammonium. After the
addition of base, the ammonia is distilled from an alkaline medium and
absorbed in boric or sulfuric acid. The ammonia may be determined
colorimetrically, by ammonia-selective electrode, or by titration with
a standard mineral acid. The 2011 editorial revision currently is
approved in Table IB for preliminary treatment of samples to be used
for determination of total Kjeldahl nitrogen (TKN).
b. 4500-Norg C-2021, Semi-Micro-Kjeldahl Method. This is a reduced-
volume version of 4500 N<INF>org</INF> B that specifies use of Kjeldahl
flasks with a capacity of 100 mL in a semi-micro-Kjeldahl digestion
apparatus equipped with heating elements to accommodate Kjeldahl flasks
and a suction outlet to vent fumes. The 2011 editorial revision
currently is approved in Table IB for preliminary treatment of samples
to be used for determination of total Kjeldahl nitrogen (TKN).
c. 4500-Norg D-2021, Block Digestion and Flow Injection Analysis.
Samples are digested in a block digestor with sulfuric acid and copper
sulfate as a catalyst. The digested sample is injected onto the FIA
manifold, where its pH is controlled by raising it to a known, basic pH
by neutralization with a concentrated buffer. This in-line
neutralization converts the ammonium cation to ammonia, and also
prevents undue influence of the sulfuric acid matrix on the pH-
sensitive color reaction that follows. The ammonia thus produced is
heated with salicylate and hypochlorite to produce a blue color that is
proportional to the ammonia concentration. The color is intensified by
adding sodium nitroprusside. The presence of EDTA in the buffer
prevents the precipitation of calcium and magnesium. The resulting
peak's absorbance is measured at 660 nm. The peak area is proportional
to the concentration of total Kjeldahl nitrogen in the original sample.
The 2011 editorial revision currently is approved

[[Page 10733]]

in Table IB for determination of total Kjeldahl nitrogen.
22. 4500-NH3 Nitrogen (Ammonia as nitrogen) Series.
a. 4500-NH3 B-2021, Preliminary Manual Distillation Step. The
sample is buffered at pH 9.5 with a borate buffer to decrease
hydrolysis of cyanates and organic nitrogen compounds. It is distilled
into a solution of boric acid when titration is to be used, or into
H<INF>2</INF>SO<INF>4</INF>, when the phenate method is used as the
determinative step. The ammonia in the distillate can be determined
either colorimetrically by the phenate method or titrimetrically with
standard H<INF>2</INF>SO<INF>4</INF> and a mixed indicator or a pH
meter. Ammonia in the distillate also can be determined by the ammonia-
selective electrode method, using 0.04 N H<INF>2</INF>SO<INF>4</INF> to
trap the ammonia. This revision replaces instructions for storage of
ammonia-free water with instructions for preparation of ammonia-free
water using an ion exchange resin and simply says that if high blank
values are produced, the analyst should prepare fresh ammonia-free
water. The 2011 editorial revision currently is approved in Table IB
for preliminary treatment of samples to be used for determination of
ammonia.
b. 4500-NH3 C-2021, Titration Method. The titrimetric method is
used only on samples that have been carried through preliminary
distillation. Ammonia is titrated with a standardized sulfuric acid
titrant using a mixed indicator of methyl red and methylene blue. The
2011 editorial revision currently is approved in Table IB for
determination of ammonia as well as for determination of total Kjeldahl
nitrogen after appropriate digestion/distillation of the sample.
c. 4500-NH3 D-2021, Electrode Method. The ammonia-selective
electrode uses a hydrophobic gas-permeable membrane to separate the
sample solution from an electrode internal solution of ammonium
chloride. Dissolved ammonia (NH<INF>3(aq)</INF> and
NH<INF>4</INF>+) is converted to NH<INF>3(aq)</INF> by
raising the pH to above 11 with a strong base. NH<INF>3(aq)</INF>
diffuses through the membrane and changes the internal solution pH that
is sensed by a pH electrode. The fixed level of chloride in the
internal solution is sensed by a chloride ion-selective electrode that
serves as the reference electrode of the sample. Potentiometric
measurements are made with a pH meter having an expanded millivolt
scale or with a specific ion meter. The 2011 editorial revision
currently is approved in Table IB for determination of ammonia, as well
as for determination of total Kjeldahl nitrogen after appropriate
digestion/distillation of the sample.
d. 4500-NH3 E-2021, Electrode Method. Ammonia is determined using
an ammonia-selective electrode. When a linear relationship exists
between concentration and response, known addition is convenient for
measuring occasional samples because no calibration is needed. Because
an accurate measurement requires that the concentration at least double
as a result of the addition, sample concentration must be known within
a factor of three. The total concentration of ammonia can be measured
in the absence of complexing agents down to 0.8 mg/L NH<INF>3</INF>-N
or in the presence of a large excess (50 to 100 times) of complexing
agent. The 2011 editorial revision currently is approved in Table IB
for determination of ammonia, as well as for determination of total
Kjeldahl nitrogen after appropriate digestion/distillation of the
sample.
e. 4500-NH3 F-2021, Phenate Method. An intensely blue compound,
indophenol, is formed by the reaction of ammonia, hypochlorite, and
phenol catalyzed by sodium nitroprusside. The color is measured
spectrophotometrically at 640 nm. The 2011 editorial revision currently
is approved in Table IB for determination of ammonia, as well as for
determination of total Kjeldahl nitrogen after appropriate digestion/
distillation of the sample.
f. 4500-NH3 G-2021, Semi-Automated Phenate Method. Alkaline phenol
and hypochlorite react with ammonia to form indophenol blue that is
proportional to the ammonia concentration. The blue color formed is
intensified with sodium nitroprusside. The color is measured
spectrophotometrically at 630 to 660 nm. The 2011 editorial revision
currently is approved in Table IB for determination of ammonia, as well
as for determination of total Kjeldahl nitrogen after appropriate
digestion/distillation of the sample.
g. 4500-NH3 H-2021, Semi-Automated Phenate Method. A water sample
containing ammonia or ammonium cation is injected into an FIA carrier
stream to which a complexing buffer (alkaline phenol) and hypochlorite
are added. This reaction, the Berthelot reaction, produces the blue
indophenol dye. The blue color is intensified by the addition of
nitroferricyanide. The resulting peak's absorbance is measured at 630
nm. The peak area is proportional to the concentration of ammonia in
the original sample. The 2011 editorial revision currently is approved
in Table IB for determination of ammonia, as well as for determination
of total Kjeldahl nitrogen after appropriate digestion/distillation of
the sample.
23. 4500-NO2- Nitrite as Nitrogen. 4500-NO<INF>2</INF>-
B-2021, Spectrophotometric Method. Nitrite (NO<INF>2</INF>-)
in a sample is determined through formation of a reddish-purple azo dye
produced at pH 2.0 to 2.5 by coupling diazotized sulfanilamide with N-
(1-naphthyl)-ethylenediamine dihydrochloride (NED) and absorbance is
measured spectrophotometrically at 543 nm. The 2011 editorial revision
currently is approved in Table IB for determination of nitrite.
24. 4500-NO3- Nitrogen (Nitrite/Nitrate as Nitrogen Series).
a. 4500-NO3- D-2019, Nitrate Electrode Method. Nitrate is measured
using an ion-selective electrode that develops a potential across a
thin, inert membrane holding in place a water-immiscible liquid ion
exchanger. The 2016 version of the method currently is approved in
Table IB for determination of nitrate.
b. 4500-NO3- E-2019, Cadmium Reduction Method. Nitrate
(NO<INF>3</INF>-) is reduced almost quantitatively to
nitrite (NO<INF>2</INF>-) in the presence of cadmium (Cd).
This method uses commercially available Cd granules treated with copper
sulfate (CuSO<INF>4</INF>) and packed in a glass column. The
NO<INF>2</INF>- is then diazotized with sulfanilamide and
coupled with NED to form a highly colored azo dye that is measured
spectrophotometrically. To correct for any NO<INF>2</INF>-
present in the sample before NO<INF>3</INF>- reduction,
samples also must be analyzed without the reduction step. The 2016
version of the method currently is approved in Table IB for
determination of nitrate (by subtraction), as well as for determination
of combined nitrate + nitrite, and for determination of nitrite singly
when bypassing the reduction step.
c. 4500-NO3- F-2019, Automated Cadmium Reduction Method. This is an
automated version of the cadmium reduction method 4500
NO<INF>3</INF>- E. Nitrate in a sample is reduced to nitrite
using cadmium reduction and then diazotized with sulfanilamide and
coupled with NED to form a highly colored azo dye that is measured
spectrophotometrically. To correct for any NO<INF>2</INF>-
present in the sample before NO<INF>3</INF>- reduction,
samples also must be analyzed without the reduction step. The 2016
version of the method currently is approved in Table IB for
determination of nitrate (by subtraction), as well as for determination
of combined nitrate +

[[Page 10734]]

nitrite, and for determination of nitrite singly when bypassing the
reduction step.
d. 4500-NO3- H-2019, Automated Hydrazine Reduction Method. Nitrate
in a sample is reduced to nitrite using hydrazine sulfate then
diazotized with sulfanilamide and coupled with NED to form a highly
colored azo dye that is measured spectrophotometrically. The 2016
version of the method currently is approved in Table IB for
determination of combined nitrate and nitrite.
e. 4500-NO3- I-2019, Cadmium Reduction Flow Injection Method. A
sample is passed through a copperized cadmium column to quantitatively
reduce its nitrate content to nitrite. The nitrite is diazotized with
sulfanilamide and coupled with NED to yield a water-soluble dye with a
magenta color whose absorbance at 540 nm is proportional to the nitrate
+ nitrite in the sample. Nitrite concentrations may be determined by
bypassing the cadmium column and nitrate concentration may be
calculated by subtraction of the result for the nitrite concentration
from the result for the combined nitrate + nitrite concentration. The
2016 version of the method currently is approved in Table IB for
determination of nitrate, as well as for determination of combined
nitrate + nitrite, and for determination of nitrite singly by bypassing
the reduction step.
25. 4500-O Oxygen (Dissolved) Series.
a. 4500-O B-2021, Iodometric Methods. A divalent manganese solution
is added and then a strong alkali is added to a sample in a glass-
stoppered bottle and dissolved oxygen (DO) rapidly oxidizes an
equivalent amount of the dispersed divalent manganous hydroxide
precipitate into higher-valency hydroxides. Oxidized manganese reverts
to the divalent state in the presence of iodide ions in an acidic
solution, liberating an amount of iodine equivalent to the original DO
content. The iodine is then titrated with a standard thiosulfate
solution. The 2016 version of the method currently is approved in Table
IB for determination of dissolved oxygen.
b. 4500-O C-2021, Azide Modification. The sample is treated with
manganous sulfate, potassium hydroxide, and potassium iodide (the
latter two reagents combined in one solution) and finally sulfuric
acid. The initial precipitate of manganous hydroxide,
Mn(OH)<INF>2</INF>, combines with the dissolved oxygen in the sample to
form a brown precipitate, manganic hydroxide, MnO(OH)<INF>2</INF>. Upon
acidification, the manganic hydroxide forms manganic sulfate, which
acts as an oxidizing agent to release free iodine from the potassium
iodide. The iodine, which is stoichiometrically equivalent to the
dissolved oxygen in the sample, is then titrated with sodium
thiosulfate or phenylarsine oxide (PAO). The azide modification
effectively removes nitrite interference, which is the most common
interference in biologically treated effluents and incubated
biochemical oxygen demand (BOD) samples. The 2016 version of the method
currently is approved in Table IB for determination of dissolved
oxygen.
c. 4500-O D-2021, Permanganate Modification. The permanganate
modification is used only on samples containing Fe(II) (e.g., acid mine
water). Concentrated sulfuric acid, potassium permanganate in solution
and potassium fluoride in solution are added to the sample. Enough
KMnO<INF>4</INF> solution is added to obtain a violet tinge that
persists for 5 minutes. 0.5 to 1.0 mL potassium oxalate solution is
then added only until permanganate color is removed completely. From
this point, the procedure closely parallels that in 4500-O C. The 2016
version of the method currently is approved in Table IB for
determination of dissolved oxygen.
d. 4500-O E-2021, Alum Flocculation Modification. Samples high in
suspended solids may consume appreciable quantities of iodine in acid
solution. The interference due to solids may be removed by alum
flocculation. Concentrated ammonium hydroxide and aluminum potassium
sulfate solution are added to a sample. The sample is allowed to settle
for about 10 min and the clear supernatant is siphoned into a 250- to
300-mL DO bottle until it overflows. From this point, the procedure
closely parallels that in 4500-O C. The 2016 version of the method
currently is approved in Table IB for determination of dissolved
oxygen.
e. 4500-O F-2021, Copper Sulfate-Sulfamic Acid Flocculation
Modification. This modification is used for biological flocs (e.g.,
activated sludge mixtures), which have high oxygen utilization rates. A
copper sulfate-sulfamic acid inhibitor solution is added to the sample.
The suspended solids are allowed to settle, and the relatively clear
supernatant liquor is siphoned into a 250- to 300-mL DO bottle. From
this point, the procedure closely parallels that in 4500-O C. The 2016
version of the method currently is approved in Table IB for
determination of dissolved oxygen.
f. 4500-O G-2021, Electrode Method. Oxygen-sensitive polarographic
or galvanic membrane electrodes are composed of two solid metal
electrodes in contact with supporting electrolyte separated from the
test solution by a selective membrane. Polyethylene and fluorocarbon
membranes are commonly used because they are permeable to molecular
oxygen and are relatively rugged. The diffusion current is linearly
proportional to the molecular-oxygen concentration. The measured
current can be converted easily to concentration units (e.g., mg/L) by
a number of calibration procedures. The 2016 version of the method
currently is approved in Table IB for determination of dissolved
oxygen.
g. 4500-O H-2021, Luminescence-based Method. The optical probe uses
luminescence-based oxygen sensors to measure the light-emission
characteristics of a luminescent reaction; oxygen quantitatively
quenches the luminescence. The change in the luminescence signal's
lifetime correlates to the DO concentration. The 2016 version of the
method currently is approved in Table IB for determination of dissolved
oxygen.
26. 4500-P Phosphorus Total and Ortho Phosphorus Series.
a. 4500-P B-2021, Digestion Sample Preparation. Because phosphorus
may occur in combination with organic matter, a digestion method to
determine total phosphorus must be able to oxidize organic matter
effectively to release phosphorus as orthophosphate. Three digestion
methods are given in 4500-P B.3, 4, and 5. The perchloric acid method
in B.5 is the most vigorous and time-consuming method, and is
recommended for particularly difficult samples, such as sediments. The
nitric acid-sulfuric acid method is recommended for most samples. The
simplest digestion method that may be used for determination of total
phosphorus is the persulfate oxidation technique in which 50 mL of an
unfiltered sample is boiled with sulfuric acid and either ammonium
persulfate or potassium persulfate for approximately 30-40 minutes or
until a final volume of about 10 mL is reached. The 2011 editorial
revision is currently approved in Table IB for preliminary treatment of
samples to be used for determination of total phosphorus as
orthophosphorus using manual or automated versions of the ascorbic acid
reduction, colorimetric methods.
b. 4500-P E-2021, Manual Method. Ammonium molybdate and antimony
potassium tartrate react in an acid medium with orthophosphate to form
phosphomolybdic acid, a heteropoly acid that is reduced to intensely
colored molybdenum blue by ascorbic acid and is measured
spectrophotometrically. This revision adds that possible interference
from silicate should be

[[Page 10735]]

evaluated when reporting concentrations less than 10 [micro]g/L. The
2011 editorial revision currently is approved in Table IB for
determination of total phosphorus after digestion of the sample, as
well as for determination of orthophosphorus in a filtered, undigested
sample.
c. 4500-P F-2021, Automated Ascorbic Acid Reduction Method.
Ammonium molybdate and antimony potassium tartrate react with
orthophosphate in an acid medium to form an antimony-phosphomolybdate
complex, which on reduction with ascorbic acid yields an intense blue
color suitable for photometric measurement using continuous flow
analytical equipment. The 2011 editorial revision currently is approved
in Table IB for determination of total phosphorus after digestion of
the sample, as well as for determination of orthophosphorus in a
filtered, undigested sample.
d. 4500-P G-2021, Automated. Ammonium molybdate and antimony
potassium tartrate react with orthophosphate in an acid medium to form
an antimony-phosphomolybdate complex, which on reduction with ascorbic
acid yields an intense blue color suitable for photometric measurement
using flow injection analysis. The 2011 editorial revision currently is
approved in Table IB for determination of total phosphorus after
digestion of the sample as well, as for determination of
orthophosphorus in a filtered, undigested sample.
e. 4500-P H-2021, Automated Total Phosphorus. Samples are manually
digested using the approved procedure for preliminary treatment of
samples to be used for determination of total phosphorus. When the
resulting solution is injected onto the manifold, the orthophosphate
ion reacts with ammonium molybdate and antimony potassium tartrate
under acidic conditions to form a complex. This complex is reduced with
ascorbic acid to form a blue complex suitable for photometric
measurement using flow injection analysis. The 2011 editorial revision
currently is approved in Table IB for determination of total
phosphorus.
27. 4500-S2- Sulfide Series.
a. 4500-S2- B-2021, Sample Pretreatment. Dissolved
sulfide is measured by first removing insoluble matter. This is done by
adding sodium hydroxide and aluminum chloride solutions producing an
aluminum hydroxide floc that is settled, leaving a clear supernatant
for analysis. The 2011 editorial revision currently is approved in
Table IB for preliminary treatment of samples to be used for
determination of sulfide.
b. 4500-S2- C-2021, Sample Pretreatment. Interferences
due to sulfite, thiosulfate, iodide, and many other soluble substances,
but not ferrocyanide, are eliminated by first precipitating zinc
sulfide (ZnS) by addition of sodium hydroxide and zinc acetate
solutions, removing the supernatant, and replacing it with reagent
water. The same procedure is used even when not needed for removal of
interferences, to concentrate sulfide prior to analysis. The 2011
editorial revision currently is approved in Table IB for preliminary
treatment of samples to be used for determination of sulfide.
c. 4500-S2- D-2021, Colorimetric Method. The methylene
blue method is based on the reaction of sulfide, ferric chloride, and
dimethyl-p-phenylenediamine to produce methylene blue. Ammonium
phosphate is added after color development to remove ferric chloride
color, which is measured photometrically. The procedure is applicable
at sulfide concentrations between 0.1 and 20.0 mg/L. There are no other
procedural changes. The 2011 editorial revision currently is approved
in Table IB for determination of sulfide.
d. 4500-S2- F-2021, Titrimetric. Iodine oxidizes sulfide
in acid solution. A titration based on this reaction is an accurate
method for determining sulfide at concentrations above 1 mg/L if
interferences are absent and if loss of H<INF>2</INF>S is avoided. The
2011 editorial revision currently is approved in Table IB for
determination of sulfide.
e. 4500-S2- G-2021, Ion-Selective Electrode Method. The
potential of a sulfide ion-selective electrode (ISE) is related to the
sulfide ion activity. An alkaline antioxidant reagent (AAR) is added to
samples and standards to inhibit oxidation of sulfide by oxygen and to
provide a constant ionic strength and pH. Use of the AAR allows
calibration in terms of total dissolved sulfide concentration. All
samples and standards must be at the same temperature. Sulfide
concentrations between 0.032 mg/L and 100 mg/L can be measured without
preconcentration. For lower concentrations, preconcentration is
necessary. The 2011 editorial revision currently is approved in Table
IB for determination of sulfide.
28. 4500-SiO2 Silica Series.
a. 4500-SiO2 C-2021, Colorimetric Method. Ammonium molybdate at pH
approximately 1.2 reacts with silica and any phosphate present to
produce heteropoly acids. Oxalic acid is added to destroy the
molybdophosphoric acid, but not the molybdosilicic acid. Even if
phosphate is known to be absent, the addition of oxalic acid is highly
desirable and is a mandatory step. The intensity of the yellow color
produced is proportional to the concentration of molybdate-reactive
silica and is measured photometrically. The 2011 editorial revision
currently is approved in Table IB for determination of silica.
b. 4500-SiO2 E-2021, Automated Method for Molybdate-Reactive
Silica. Ammonium molybdate at pH approximately 1.2 reacts with silica
and any phosphate present to produce heteropoly acids. Oxalic acid is
added to destroy the molybdophosphoric acid, but not the molybdosilicic
acid. The yellow molybdosilicic acid is reduced by means of amino
naphthol sulfonic acid to heteropoly blue. The blue color is more
intense than the yellow color of 4500-SiO<INF>2</INF> C and provides
increased sensitivity. The 2011 editorial revision currently is
approved in Table IB for determination of silica.
c. 4500-SiO2 F-2021, Automated Method for Molybdate-Reactive
Silicate. Silicate reacts with molybdate under acidic conditions to
form yellow beta-molybdosilicic acid. This acid is subsequently reduced
with stannous chloride to form a heteropoly blue complex that is
measured photometrically. Oxalic acid is added to reduce the
interference from phosphate. The 2011 editorial revision currently is
approved in Table IB for determination of silica.
29. 4500-SO42-Sulfate Series.
a. 4500-SO42-C-2021, Gravimetric Method with Ignition of Residue.
Sulfate is precipitated in a hydrochloric acid (HCl) solution as barium
sulfate (BaSO<INF>4</INF>) by the addition of barium chloride
(BaCl<INF>2</INF>). The precipitation is carried out near the boiling
temperature, and after a period of digestion, the precipitate is
filtered, washed with water until free of Cl-, ignited at
800 [deg]C for an hour and weighed as BaSO<INF>4</INF>. The 2011
editorial revision currently is approved in Table IB for determination
of sulfate.
b. 4500-SO42-D-2021, Gravimetric Method with Drying of Residue.
Sulfate is precipitated in a hydrochloric acid (HCl) solution as barium
sulfate (BaSO<INF>4</INF>) by the addition of barium chloride
(BaCl<INF>2</INF>). The precipitation is carried out near the boiling
temperature, and after a period of digestion the precipitate is
filtered, washed with water until free of Cl-, dried to a
constant weight in an oven at 105 [deg]C or higher, and weighed as
BaSO<INF>4</INF>. The 2011 editorial revision currently is approved in
Table IB for determination of sulfate.
c. 4500-SO42-E-2021, Turbidimetric Method. Sulfate ion
(SO<INF>4</INF>2-) is precipitated in an acetic acid medium

[[Page 10736]]

with barium chloride (BaCl<INF>2</INF>) to form barium sulfate
(BaSO<INF>4</INF>) crystals of uniform size. Light absorbance of the
BaSO<INF>4</INF> suspension is measured by a photometer and the
SO<INF>4</INF>2- concentration is determined by comparison
of the reading with a standard curve. The 2011 editorial revision
currently is approved in Table IB for determination of sulfate.
d. 4500-SO42-F-2021, Automated Colorimetric Method. Barium sulfate
is formed by the reaction of the SO<INF>4</INF>2- with
barium chloride (BaCl<INF>2</INF>) at a low pH. At high pH, excess
barium reacts with methylthymol blue (MTB) to produce a blue chelate.
The uncomplexed methylthymol blue is gray. The intensity of gray
(uncomplexed methylthymol blue) is measured photometrically and is
proportional to concentration of sulfate. The 2011 editorial revision
currently is approved in Table IB for determination of sulfate.
e. 4500-SO42-G-2021, Automated Colorimetric Method. At pH 13.0,
barium forms a blue complex with MTB. The sample is injected into a
low, but known, concentration of sulfate. The sulfate from the sample
then reacts with the ethanolic barium-MTB solution and displaces the
MTB from the barium to give barium sulfate and uncomplexed MTB.
Uncomplexed MTB has a grayish color. The pH is raised with NaOH and the
gray color of the uncomplexed MTB is measured photometrically. The
intensity of the gray color is proportional to the sulfate
concentration. The 2011 editorial revision currently is approved in
Table IB for determination of sulfate.
30. Sulfite 4500-SO32-B-2021, Titrimetric Iodometric Method. An
acidified sample containing sulfite (SO<INF>3</INF>2-) is
titrated with a standardized potassium iodide-iodate titrant. Free
iodine, liberated by the iodide-iodate reagent, reacts with
SO<INF>3</INF>2-. The titration endpoint is signaled by the
blue color resulting from the first excess of iodine reacting with a
starch indicator. The 2011 editorial revision currently is approved in
Table IB for determination of sulfite.
31. 5520 Oil and Grease Series.
a. 5520 B-2021, Liquid-Liquid, Partition-Gravimetric Method.
Dissolved or emulsified oil and grease is extracted from water by
intimate contact with an extracting solvent (n-hexane). The extract is
dried over sodium sulfate. The solvent is then distilled from the
extract and the hexane extractable material is desiccated and weighed.
Some extractables, especially unsaturated fats and fatty acids, oxidize
readily; hence, special precautions regarding temperature and solvent
vapor displacement are included to minimize this effect. Organic
solvents shaken with some samples may form an emulsion that is very
difficult to break. This method includes a means for handling such
emulsions. Recovery of solvents is discussed. Solvent recovery can
reduce both vapor emissions to the atmosphere and costs. The 2011
editorial revision currently is approved in Table IB for determination
of oil and grease (hexane extractable material or HEM).
b. 5520 F-2021, Hydrocarbons. The oil and grease extracted by 5520
B is used for this test. When only hydrocarbons are of interest, this
procedure is introduced before final measurement. When hydrocarbons are
to be determined after total oil and grease has been measured,
redissolve the extracted oil and grease in n-hexane. Silica gel has the
ability to adsorb polar materials. The solution of extracted
hydrocarbons and fatty materials in n-hexane is mixed with silica gel,
and the fatty acids are removed selectively from solution. The solution
is filtered to remove the silica gel, the solvent is distilled, and the
silica gel treated hexane extractable material (SGT-HEM) is weighed.
The materials not eliminated by silica gel adsorption are designated
hydrocarbons by this test. The 2011 editorial revision currently is
approved in Table IB for determination of oil and grease (hexane
extractable material or HEM).
32. 5530 Phenols Series.
a. 5530 B-2021, Manual Distillation. Phenols, defined as hydroxy
derivatives of benzene and its condensed nuclei, may occur in domestic
and industrial wastewaters, natural waters, and potable water supplies.
Phenols are distilled from nonvolatile impurities. Because the
volatilization of phenols is gradual, the distillate volume must
ultimately equal that of the original sample. The 2010 version of the
method currently is approved in Table IB for preliminary treatment of
samples to be used for determination of phenols.
b. 5530 D-2021, Colorimetric Method. Steam-distillable phenolic
compounds react with 4-aminoantipyrine at pH 7.9 <plus-minus> 0.1 in
the presence of potassium ferricyanide to form a colored antipyrine
dye. This dye is kept in aqueous solution and the absorbance is
measured photometrically at 500 nm. The 2010 version of the method
currently is approved in Table IB for determination of phenol. Note
that for regulatory compliance monitoring required under the Clean
Water Act, the colorimetric reaction must be performed at a pH of 10.0
<plus-minus> 0.2 as stated in 40 CFR 136.3, Table IB, footnote 27.
33. 5540 Surfactants.
5540 C-2021. This colorimetric method comprises three successive
extractions from an acid aqueous medium containing excess methylene
blue into chloroform (CHCl<INF>3</INF>), followed by an aqueous
backwash and measurement of the blue color in the CHCl<INF>3</INF> by
spectrophotometry at 652 nm. The method is applicable at methylene blue
active substances concentrations down to about 0.025 mg/L. The 2011
editorial revision currently is approved in Table IB for determination
of surfactants.
34. 6200 Volatile Organic Compounds Series.
a. In the 6200 B-2020, Purge and Trap Capillary-Column Gas
Chromatographic/Mass Spectrometric (GC/MS) Method, volatile organic
compounds are transferred efficiently from the aqueous to the gaseous
phase by bubbling an inert gas (e.g., helium) through a water sample
contained in a specially designed purging chamber at ambient
temperature. The vapor is swept through a sorbent trap that adsorbs the
analytes of interest. After purging is complete, the trap is heated and
back-flushed with the same inert gas to desorb the compounds onto a gas
chromatographic column. The gas chromatograph is temperature-programmed
to separate the compounds. The detector is a mass spectrometer. The
2011 editorial revision currently is approved in Table IC for
determination of benzene, bromodichloromethane, bromoform,
bromomethane, carbon tetrachloride, chlorobenzene, chloroethane,
chloroform, chloromethane, dibromochloromethane, 1,2-dichlorobenzene,
1,3-dichlorobenzene, 1,4-dichlorobenzene, dichlorodifluoromethane, 1,1-
dichloroethane, 1,2-dichloroethane, 1,1-dichloroethene, trans-1,2-
dichloroethene, 1,2-dichloropropane, cis-1,3-dichloropropene, trans-
1,3-dichloropropene, ethylbenzene, methylene chloride, 1,1,2,2-
tetrachloroethane, tetrachloroethene, toluene, 1,1,1-trichloroethane,
1,1,2-trichloroethane, trichloroethene, trichlorofluoromethane, and
vinyl chloride.
b. 6200 C-2020, Purge and Trap Capillary-Column Gas Chromatographic
(GC) Method. Volatile organic compounds are transferred efficiently
from the aqueous to the gaseous phase by bubbling an inert gas (e.g.,
helium) through a water sample contained in a specially designed
purging chamber at ambient temperature. The vapor is swept through a
sorbent trap that adsorbs the analytes of interest. After

[[Page 10737]]

purging is complete, the trap is heated and back-flushed with the same
inert gas to desorb the compounds onto a gas chromatographic column.
The gas chromatograph is temperature-programmed to separate the
compounds and detected using a photoionization detection and an
electrolytic conductivity detection in series. The 2011 editorial
revision currently is approved in Table IC for determination of
benzene, bromodichloromethane, bromoform, bromomethane, carbon
tetrachloride, chlorobenzene, chloroethane, chloroform, chloromethane,
dibromochloromethane, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-
dichlorobenzene, 1,1-dichloroethane, 1,2-dichloroethane, 1,1-
dichloroethene, trans-1,2-dichloroethene, 1,2-dichloropropane, cis-1,3-
dichloropropene, trans-1,3-dichloropropene, ethylbenzene, methylene
chloride, 1,1,2,2-tetrachloroethane, tetrachloroethene, toluene, 1,1,1-
trichloroethane, 1,1,2-trichloroethane, trichloroethene,
trichlorofluoromethane, and vinyl chloride.
35. 6410 Extractable Base/Neutrals and Acids.
6410 B-2020, Liquid-Liquid Extraction Gas Chromatographic/Mass
Spectrometric Method. This method is applicable to the determination of
organic compounds that are partitioned into an organic solvent and are
amenable to gas chromatography in municipal and industrial discharges.
A measured volume of sample is extracted serially with methylene
chloride at a pH of approximately 2 and again at pH 11. The extract is
dried, concentrated, and analyzed by GC/MS. Qualitative compound
identification is based on retention time and relative abundance of
three characteristic masses (m/z). Quantitative analysis uses internal-
standard techniques with a single characteristic m/z. This revision
adds a note that although the method was validated extracting base
neutrals first and then acids, performance may be improved by
extracting acids first and then base neutrals. In addition, EPA
proposes to approve method 6410-B for endrin aldehyde in Table ID. This
parameter was inadvertently left off the 2000 MUR rulemaking. The 2000
version of the method currently is approved in Table IC for
determination of acenaphthene, acenaphthylene, anthracene, benzidine,
benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene,
benzo(g,h,i)perylene, benzo(k)fluoranthene, butyl benzyl phthalate,
bis(2-chloroethoxy) methane, bis(2-chloroethyl) ether, bis(2-
ethylhexyl) phthalate, bromodichloromethane, 4-bromophenyl phenyl
ether, 4-chloro-3-methyl phenol, 2-chloronaphthalene, 2-chlorophenol,
4-chlorophenyl phenyl ether, chrysene, dibenzo(a,h)anthracene, 3,3'-
dichlorobenzidine, 2,4-dichlorophenol, diethyl phthalate, 2,4-
dimethylphenol, dimethyl phthalate, di-n-butyl phthalate, di-n-octyl
phthalate, 2,4-dinitrophenol, 2,4-dinitrotoluene, 2,6-dinitrotoluene,
fluoranthene, fluorene, hexachlorobenzene, hexachlorobutadiene,
hexachlorocyclopentadiene, indeno(1,2,3-c,d) pyrene, isophorone, 2-
methyl-4,6-dinitrophenol, naphthalene, nitrobenzene, 2-nitrophenol, 4-
nitrophenol, n-nitrosodi-n-propylamine, n-nitrosodiphenylamine, PCB-
1016, PCB-1221, PCB-1232, PCB-1242, PCB-1248, PCB-1254, PCB-1260,
pentachlorophenol, phenanthrene, phenol, pyrene, 1,2,4-
trichlorobenzene, and 2,4,6-trichlorophenol and in Table ID for
determination of aldrin, [alpha]-BHC, [beta]-BHC, [delta]-BHC, [gamma]-
BHC (lindane), chlordane, 4,4'-DDD, 4,4'-DDE, 4,4'-DDT, dieldrin,
endosulfan I, endosulfan II, endosulfan sulfate, endrin, heptachlor,
heptachlor epoxide, and toxaphene.
36. 6420 Phenols.
6420 B-2020, Liquid-Liquid Extraction Gas Chromatographic Method. A
measured volume of sample is acidified and extracted with methylene
chloride. The extract is dried and exchanged to 2-propanol during
concentration. Target analytes in the extract are separated by gas
chromatography and are identified by retention time and measured with a
flame ionization detector, or derivatized and measured with an electron
capture detector. This revision of the method replaces distilled,
deionized water with reagent water, adds that the packed columns used
for validation of the method are no longer available or recommended,
and includes information on alternative capillary columns that may be
used. The 2000 version of the method currently is approved in Table IC
for determination of 4-chloro-3-methylphenol, 2-chlorophenol, 2,4-
dichlorophenol, 2,4-dimethylphenol, 2,4-dinitrophenol, 2-methyl-4,6-
dinitrophenol, 2-nitrophenol, 4-nitrophenol, pentachlorophenol, phenol,
and 2,4,6-trichlorophenol.
37. 6440 Polynuclear Aromatic Hydrocarbons.
6440 B-2021, Liquid-Liquid Extraction Chromatographic Method. A
measured volume of sample is extracted with methylene chloride. The
extract is dried, concentrated, and separated by the high-performance
liquid chromatographic (HPLC) or gas chromatographic (GC) method.
Ultraviolet (UV) and fluorescence detectors are used with HPLC to
identify and measure the polynuclear aromatic hydrocarbons. A flame
ionization detector is used with GC. The 2005 version of the method
currently is approved in Table IC for determination of acenaphthene,
acenaphthylene, anthracene, benzo(a)anthracene, benzo(a)pyrene,
benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene,
chrysene, dibenzo(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-
c,d)pyrene, naphthalene, phenanthrene, and pyrene.
38. 6630 Organochlorine Pesticides Series.
a. 6630 B-2021, Liquid-Liquid Extraction Gas Chromatographic Method
I, in this procedure, the pesticides are extracted with a mixed
solvent, diethyl ether-hexane or methylene chloride-hexane, by either
liquid-liquid extraction using a separatory funnel or by continuous
liquid-liquid extraction. The extract is concentrated by evaporation
and, if necessary, is cleaned up by column adsorption chromatography.
The individual pesticides then are separated by gas chromatography and
the compounds are measured with an electron capture detector (ECD).
This revision of the method adds information regarding alternative
capillary columns that may be used in place of the packed columns that
were used for validation of the method, removes information regarding
preparation of packed columns, replaces information regarding manual
injection technique with use of an autosampler and states that gas
chromatography/mass spectrometry (GC/MS) may be used for confirmatory
analyses in place of a second column and ECD detection. There are no
other procedural changes. The 2007 version of the method currently is
approved in Table ID for determination of aldrin, [alpha]-BHC, [beta]-
BHC, [delta]-BHC, [gamma]-BHC (lindane), captan, carbophenothion,
chlordane, 4,4'-DDD, 4,4'-DDE, 4,4'-DDT, dichloran, dieldrin,
endosulfan I, endosulfan II, endrin, heptachlor, heptachlor epoxide,
isodrin, malathion, methoxychlor, mirex, parathion methyl, parathion
ethyl, PCNB, strobane, toxaphene, and trifluralin.
b. In 6630 C-2021, Liquid-Liquid Extraction Gas Chromatographic
Method II, a measured volume of sample is extracted with methylene
chloride either by liquid-liquid extraction using separatory funnels or
by continuous liquid-liquid extraction. The extract is dried and
exchanged to

[[Page 10738]]

hexane during concentration. The target analytes are separated by gas
chromatography and the compounds are measured with an electron capture
detector (ECD). This revision of the method adds information regarding
alternative capillary columns that may be used in place of the packed
columns that were used for validation of the method, and states that
gas chromatography/mass spectrometry (GC/MS) may be used for
confirmatory analyses in place of a second column and ECD detection.
There are no other procedural changes. The 2007 version of the method
currently is approved in Table ID for determination of aldrin, [alpha]-
BHC, [beta]-BHC, [delta]-BHC, [gamma]-BHC (lindane), chlordane, 4,4'-
DDD, 4,4'-DDE, 4,4'-DDT, dieldrin, endosulfan I, endosulfan II,
endosulfan sulfate, endrin, endrin aldehyde, heptachlor, heptachlor
epoxide, isodrin, methoxychlor, mirex, PCNB, strobane, and toxaphene.
39. 6640 Acidic Herbicide Compounds.
6640 B-2021, Micro Liquid-Liquid Extraction Gas Chromatographic
Method. A 40-mL sample is adjusted to pH >=12 with 4 N sodium hydroxide
and is kept for 1 hour at room temperature to hydrolyze derivatives.
Because the chlorphenoxy acid herbicides are formulated as a variety of
esters and salts, the hydrolysis step is required and may not be
skipped. The aqueous sample then is acidified with sulfuric acid to pH
<=1 and extracted with 4 mL of methyl tert-butyl ether (MtBE) that
contains the internal standard. The chlorinated acids, which have been
partitioned into the MtBE, then are converted to methyl esters by
derivatization with diazomethane. The target esters are separated and
detected by capillary column gas chromatography using an electron
capture detector (GC/ECD). Analytes are quantified using an internal-
standard-based calibration curve. The 2006 editorial revision currently
is approved in Table IC for determination of 2,4-D, 2,4,5-T, and 2,4,5-
TP (Silvex).

D. Changes to 40 CFR 136.3 To Include Alternate Test Procedures in
Table IC

To promote method innovation, EPA maintains a program that allows
method developers to apply for EPA review and potential approval of an
alternative method to an existing approved method. This alternate test
procedure (ATP) program is described for CWA applications at 40 CFR
136.4 and 136.5. EPA is proposing two ATPs for nationwide use. Based on
EPA's review, the performance of these ATPs is equally effective as
other methods already approved for measurement of 2,3,7,8-substituted
tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofurans
(PCDDs/PCDFs) in wastewater. The ATP applicants supplied EPA with study
reports that contain the data from their validation studies. These
study reports, the final methods, and the letters documenting EPA's
review are included as supporting documents in the docket for this
proposed rule.
These proposed new methods are: SGS AXYS Method ATM 16130,
``Determination of 2,3,7,8-Substituted Tetra- through Octa-Chlorinated
Dibenzo-p-Dioxins and Dibenzofurans (CDDs/CDFs) Using Waters and
Agilent Gas Chromatography-Tandem-Mass Spectrometry (GC/MS/MS),
Revision 1.0 and Pace Analytical Method PAM-16130-SSI, ``Determination
of 2,3,7,8-Substituted Tetra- through Octa-Chlorinated Dibenzo-p-
Dioxins and Dibenzofurans (CDDs/CDFs) Using Shimadzu Gas Chromatography
Mass Spectrometry (GC-MS/MS), Revision 1.1.'' These ATPs are the
results of separate collaborative efforts between SGS AXYS Analytical
Services Ltd, and the instrument manufacturers Waters Corporation,
Agilent Technologies, and between Pace Analytical Services LLC and the
instrument manufacturer Shimadzu Scientific Instruments, Inc. These
final methods are heavily adapted from Method 1613B. Neither ATP makes
changes to the extraction or cleanup procedures specified in Method
1613B. All required quality control tests (or analogous tests) and
associated QC acceptance criteria have been included in both SGS AXYS
16130 and PAM-16130-SSI.
To minimize costs to both the applicants and the Agency where
possible, SGS AXYS, Pace Analytical, and the instrument manufacturers
who collaborated on these methods worked closely with EPA's CWA ATP
Coordinator to design single-laboratory validation studies for these
methods. The goal of these validation studies was to demonstrate that
all of the performance criteria specified in Method 1613B could be met
and that comparable performance could be achieved when using GC-MS/MS
instrumentation for determination of PCDDs/PCDFs in extracts from real-
world samples.
EPA Method 1613B was promulgated at 40 CFR 136 in 1995 and remains
the only approved method for dioxins and furans at NPDES permit levels
(Methods 613 and 625.1 may only be used for screening). Method 1613B is
also the only method approved at 40 CFR part 136 that relies on gas
chromatography-high resolution mass spectrometry (GC/HRMS) as the
determinative technique. As a result, the need for GC/HRMS instruments
is somewhat limited, and market forces have led some instrument vendors
to move away from supporting new GC/HRMS instrumentation. In addition,
in the last 30 years, there has been substantial consolidation of
manufacturers, with the disappearance of many of the vendors whose
instruments were used to develop and validate Method 1613B.
In these two methods, referred to in the rule as ATM 16130 and PAM
16130-SSI, each sample is spiked with the same suite of carbon-13
labeled standards prior to extraction and those standards are used for
isotope dilution quantitation in the same way as is done in EPA Method
1613B. All of the relevant QC acceptance criteria are the same in the
methods as well. The difference between these methods and the approved
EPA method is the use of an MS/MS detector system that uses Multiple
Reaction Monitoring (MRM) in place of a high resolution mass
spectrometer (HRMS) detector system. The GC portions of the methods did
not change.

E. Corrections or Amendments to the Text and Tables of 40 CFR Part 136

In addition to the method revisions discussed in Section II.C of
this preamble, Standard Methods has revised certain of their general
quality control sections (2020, 3020, 4020 and 5020). EPA is proposing
to update the year of the current references to these sections in 136.3
Table IB footnote 85, as well as add a reference to an additional
Standard Methods Quality Control Section: Part 6000 Individual Organic
Compounds, 6020, based on EPA's review of these sections. These Quality
Control Standards are available for download at <a href="http://www.standardmethods.org">www.standardmethods.org</a>
at no charge. Further, during the preparation of this proposed
rulemaking, EPA identified several minor errors or inconsistencies in
the tables of approved methods. Therefore, EPA is proposing the
following changes to 40 CFR 136.3, Tables IA, IB, IC or ID:
1. Table IA. Removing the units of ``number per 100 mL'' under
parameter 1. Coliform (fecal), because parameter 1 is specifically for
biosolids that are reported as ``number per gram dry weight''.
2. Table IA. Moving USGS Method ``B-0050-85'' from parameter 1.
Coliform (fecal) number per gram dry weight to parameter 2. Coliform
(fecal) number per 100 mL, to address an error from the previous
rulemaking when Parameter 1 Coliform (fecal) was split

[[Page 10739]]

into two parameters to eliminate confusion as to which methods were
approved for biosolids.
3. Table IA. Moving the phrase ``two-step'' in parameter 3, in the
``Method'' column from the second to the third line which returns the
phrase to the proper line after having been inadvertently moved.
4. Table IB. Revising footnote 85 to remove bullet formatting.
5. Table IB. EPA proposes adding footnote 86 to Method 419D, listed
as an approved method for determination nitrate using Colorimetric
(Brucine sulfate) methodology. This addition corrects a long-standing
typographical error regarding the appropriate footnote for this method
in Table IB.
6. Table IB. Correcting an inadvertent error to footnote 57. The
reference number was incorrectly changed to 335.4-1. The correct number
is 335.4.
7. Tables IC and ID. Proposes adding footnote 15 to the Standard
Method Column header and adding footnote 15 to refer to Quality Control
Section: Part 6000 Individual Organic Compounds, 6020 (2019).
8. Table IC. The parameter 39, dichlorodifluoromethane, should
refer to Method 6200 B rather than 6200 C for the GC/MS method.
9. Table IC. Parameters 66-72, 95, 96 and 97. These parameters are
missing the footnote 10 that was inadvertently dropped in an earlier
rulemaking. Footnote 10 to table IC applies to all of the 17 dioxin and
furan congeners.
10. Table IH. Parameter 2 has method B-0025-85 is moved down one
row because it was inadvertently moved. This method is a one-step
membrane filtration (MF) method rather than a most probable number
(MPN) method.
11. Footnote 5 to Table II for the preservation and holding time
requirements for cyanide to add the year (2015) of the ASTM method
D7365-09a (15). This practice is applicable for the collection and
preservation of water samples for the analysis of cyanide. Samples are
collected in appropriate containers and mitigated for known
interferences either in the field during sample collection or in the
laboratory prior to analysis. The sampling, preservation and mitigation
of interference procedures described in this practice are recommended
for the analysis of total cyanide, available cyanide, weak acid
dissociable cyanide, and free cyanide by ASTM Methods D2036, D4282,
D4374, D6888, D6994, D7237, D7284, and D7511.
The recommended sampling and preservation procedures in the ASTM
method have not changed since 2009, but the change to footnote 5 will
simplify identification of the current method that is available from
ASTM International. The 2015 reapproval date was already updated in
footnote 6 to Table II in the 2021 methods update rule; however, adding
the reapproval date was overlooked in the IBR section and in footnote 5
to Table II.

F. Changes to 40 CFR 136.3 To Include New Standard Methods Committee
Methods Based on Previously Approved Technologies

EPA is proposing adding five new methods in furtherance of the
National Technology Transfer and Advancement Act of 1995 (NTTAA),
Public Law 104-113, that provides that Federal agencies and departments
shall use technical standards developed or adopted by the VCSBs if
compliance would not be inconsistent with applicable law or otherwise
impracticable. These methods were submitted by Standard Methods and are
consistent with other already approved methods. EPA is adding 4500-
CN- P-2021, 4500-CN- Q-2021, 4500 CN-
R-2021, 4500-F- G-2021 to Table IB for cyanide and fluoride
and is adding 5520 G-2021 to Table IB for oil and grease, based on the
following reasons:
1. Cyanide. Although method 4500-CN- P-2021, Total
Cyanide by Segmented Flow Injection, UV-Irradiation with Gas Diffusion,
and Amperometric Measurement is new to Standard Methods for the
Examination of Water and Wastewater, it is based on ASTM D7511-12(17),
which is approved in Table IB for determination of total cyanide and
relies on the same underlying chemistry and determinative technique to
determine total cyanide. Total cyanide consists of dissolved HCN,
sodium cyanide (NaCN), and various metal-cyanide complexes, which a
continuous flow analyzer converts to aqueous HCN by mixing it with
sulfuric acid, irradiating with UV light, and precipitating potentially
interfering sulfides with bismuth ion. The aqueous HCN is captured in a
donor stream that is passed across a hydrophobic gas-permeable
membrane, which selectively diffuses the gaseous HCN into a parallel
acceptor stream of dilute sodium hydroxide forming dissolved
CN-. The cyanide ion in this acceptor stream is measured
using an amperometric detector, where the cyanide ion dissolves the
silver electrode, resulting in a proportional current.
2. 4500-CN- Q-2021, Weak and Dissociable Cyanide by Flow Injection,
Gas Diffusion, and Amperometric Measurement. Weak and dissociable
cyanide consists of dissolved HCN, NaCN, and various metal-cyanide
complexes and includes the same forms of cyanide as those measured
using other methods approved in Table IB for determination of available
cyanide. Analysts pretreat for weak and dissociable cyanide by mixing a
sample with ligand reagents. They then inject the sample into a
sulfuric acid and bismuth nitrate solution to produce a donor stream
containing aqueous dissolved HCN and precipitated sulfide, if sulfide
is present. The donor stream is passed across a hydrophobic gas-
permeable membrane, which selectively diffuses gaseous HCN into a
parallel acceptor stream of dilute sodium hydroxide, forming dissolved
CN-. The cyanide ion in this acceptor stream is measured using an
amperometric detector, where the cyanide ion dissolves the silver
electrode, resulting in a proportional current. Although this method is
new to Standard Methods for the Examination of Water and Wastewater, it
is based on ASTM D6888-16, which is approved in Table IB for
determination of available cyanide and relies on the same underlying
chemistry and determinative technique to determine available cyanide.
3. 4500-CN- R-2021, Free Cyanide by Flow Injection, Gas Diffusion,
and Amperometric Measurement. Free cyanide (FCN) consists of dissolved
HCN, NaCN, and the soluble fraction of various metal-cyanide complexes.
To determine FCN, analysts pretreat a sample by mixing it with a
buffered solution in the pH range of 6 to 8 that simulates the
receiving water resulting in a donor stream containing aqueous
dissolved HCN in equilibrium with the cyanide anion. The donor stream
is passed across a hydrophobic gas-permeable membrane, which
selectively diffuses gaseous HCN into a parallel acceptor stream that
consists of dilute sodium hydroxide, forming dissolved CN-. The cyanide
ions in this acceptor stream are measured when it is passed through an
amperometric detector, where the cyanide ion dissolves the silver
electrode, resulting in a proportional current. Although this method is
new to Standard Methods for the Examination of Water and Wastewater, it
is based on ASTM D7237-15, which is approved in Table IB for
determination of free cyanide and relies on the same underlying
chemistry and determinative technique to determine free cyanide.
4. Fluoride. 4500-F- G-2021, Ion-Selective Electrode Flow Injection
Analysis is an automated version of method 4500-F- C and
relies on the same underlying chemistry and

[[Page 10740]]

determinative technique as USGS Method I-4237-85, which currently is
approved in Table IB for determination of fluoride. Fluoride is
determined potentiometrically by using a combination fluoride ion
selective electrode (ISE) in a flow cell. The fluoride electrode
consists of a lanthanum fluoride crystal across which a potential is
developed by fluoride ions.
5. Oil and Grease. In 5520 G-2021, Solid-Phase, Partition-
Gravimetric Method, dissolved or emulsified oil and grease is extracted
from water by passing a sample through a solid-phase extraction (SPE)
disk where the oil and grease are adsorbed by the disk and subsequently
eluted with n-hexane. SPE is a modification allowed under EPA Methods
1664 A and B and relies on the same underlying chemistry and
determinative technique as Methods 1664 A and B. Some extractables,
especially unsaturated fats and fatty acids, oxidize readily; hence,
special precautions regarding temperature and solvent vapor
displacement are provided. This method is not applicable to materials
that volatilize at temperatures below 85 [deg]C, or crude and heavy
fuel oils containing a significant percentage of material not soluble
in n-hexane. This method may be a satisfactory alternative to liquid-
liquid extraction techniques, especially for samples that tend to form
difficult emulsions during the extraction step.

IV. Incorporation by Reference

Currently, hundreds of methods and ATPs are incorporated by
reference within 40 CFR part 136. In most cases, 40 CFR part 136
contains multiple approved methods for a single parameter (or
pollutant) and regulated entities often have a choice in selecting a
method. The proposed rule contains revisions to VCSB methods that are
currently incorporated by reference (see Sections III.B, III.C, and
III.F of this preamble). Two VCSBs have made such revisions, Standard
Methods and ASTM. The proposed VCSB methods are consistent with the
requirements of the National Technology Transfer and Advancement Act
(NTTAA), under which Federal agencies use technical standards developed
or adopted by the VCSBs if compliance would not be inconsistent with
applicable law or otherwise impracticable (see Section V.I of this
preamble). The proposed copyrighted VCSB methods are available on their
respective websites (<a href="http://standardmethods.org">standardmethods.org</a> and <a href="http://astm.org">astm.org</a>) to everyone at a
cost determined by the VCSB, generally from $60 to $80. Both
organizations also offer memberships or subscriptions that allow
unlimited access to their methods. The cost of obtaining these methods
is not a significant financial burden for a discharger or environmental
laboratory, making the methods reasonably available.
This proposal also includes two vendor ATPs (see Section III.D of
this preamble) and four revised EPA methods (see Section III.A of this
preamble) which EPA proposes to incorporate by reference. The ATPs and
EPA methods are available free of charge on their respective websites
(<a href="http://sgsaxys.com/wp-content/uploads/2022/09/SGS-AXYS-Method-16130-Rev-1.0.pdf">sgsaxys.com/wp-content/uploads/2022/09/SGS-AXYS-Method-16130-Rev-1.0.pdf</a>, <a href="http://pacelabs.com">pacelabs.com</a> and <a href="http://epa.gov/cwa-methods/approved-cwa-chemical-test-methods">epa.gov/cwa-methods/approved-cwa-chemical-test-methods</a>), therefore the ATPs and EPA methods incorporated by
reference are reasonably available.

V. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review Executive
Order 13563: Improving Regulation and Regulatory Review

This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.

B. Paperwork Reduction Act

This action does not impose an information collection burden under
the Paperwork Reduction Act. This rule does not impose any information
collection, reporting, or recordkeeping requirements. This proposal
would merely add or revise CWA test procedures.

C. Regulatory Flexibility Act

The Agency certifies that this action would not have a significant
economic impact on a substantial number of small entities under the
Regulatory Flexibility Act. This action would not impose any
requirements on small entities. This action would approve new and
revised versions of CWA testing procedures. Generally, these changes
would have a positive impact on small entities by increasing method
flexibility, thereby allowing entities to reduce costs by choosing more
cost-effective methods. In general, EPA expects the proposed revisions
would lead to few, if any, increased costs. The proposed changes
clarify or improve the instructions in the method, update the
technology used in the method, improve the QC instructions, make
editorial corrections, or reflect the most recent approval year of an
already approved method. In some cases, the proposal would add
alternatives to currently approved methods for a particular analyte
(e.g., ASTM Method D7511). Because these methods would be alternatives
rather than requirements, there are no direct costs associated with
this proposal. EPA proposes methods that would be incorporated by
reference. If a permittee elected to use these methods, they could
incur a small cost associated with obtaining these methods from the
listed sources. See Section IV of this preamble.

D. Unfunded Mandates Reform Act

This action does not contain any unfunded mandate as described in
the Unfunded Mandates Reform Act, 2 U.S.C. 1531-1538, and does not
significantly or uniquely affect small governments. The action imposes
no enforceable duty on any state, local or tribal governments or the
private sector.

E. Executive Order 13132: Federalism

This proposed rule does not have federalism implications. It would
not have substantial direct effects on the states, on the relationship
between the national government and the states, or on the distribution
of power and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

This proposed rule does not have tribal implications as specified
in Executive Order 13175. This rule would merely approve new and
revised versions of test procedures. EPA does not expect the proposal
would lead to any costs to any tribal governments, and if incurred, EPA
projects they would be minimal. Thus, Executive Order 13175 does not
apply to this action.

G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that EPA has reason to believe may disproportionately affect children,
per the definition of ``covered regulatory action'' in section 2-202 of
the Executive Order. This action is not subject to Executive Order
13045 because it does not concern an environmental health risk or
safety risk.

H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use

This action is not subject to Executive Order 13211 because it is
not a

[[Page 10741]]

significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act of 1995

This action involves technical standards. EPA proposes to approve
the use of technical standards developed and recommended by the
Standard Methods Committee and ASTM International for use in compliance
monitoring where EPA determined that those standards meet the needs of
CWA programs. As described above, this proposal is consistent with the
NTTAA.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

Executive Order 12898 (59 FR 7629, February 16, 1994) directs
Federal agencies, to the greatest extent practicable and permitted by
law, to make environmental justice part of their mission by identifying
and addressing, as appropriate, disproportionately high and adverse
human health or environmental effects of their programs, policies, and
activities on minority populations (people of color) and low-income
populations.
EPA believes that this type of action does not concern human health
or environmental conditions and therefore cannot be evaluated with
respect to potentially disproportionate and adverse effects on people
of color, low-income populations and/or indigenous peoples. This action
has no effect on human health or the environment because this action
would approve new and revised versions of CWA testing procedures. The
proposed changes clarify or improve the instructions in the method,
update the technology used in the method, improve the QC instructions,
make editorial corrections, or reflect the most recent approval year of
an already approved method. These proposed changes would provide
increased flexibility for the regulated community in meeting monitoring
requirements while improving data quality. In addition, this proposed
update to the CWA methods would incorporate technological advances in
analytical technology.

List of Subjects in 40 CFR Part 136

Environmental protection, Incorporation by reference, Reporting and
recordkeeping requirements, Test procedures, Water pollution control.

Michael S. Regan,
Administrator.
For the reasons set out in the preamble, the EPA proposes to amend
40 CFR part 136 as follows:

PART 136--GUIDELINES ESTABLISHING TEST PROCEDURES FOR THE ANALYSIS
OF POLLUTANTS

0
1. The authority citation for part 136 continues to read as follows:

Authority: Secs. 301, 304(h), 307 and 501(a), Pub. L. 95-217, 91
Stat. 1566, et seq. (33 U.S.C. 1251, et seq.) (the Federal Water
Pollution Control Act Amendments of 1972 as amended by the Clean
Water Act of 1977).
0
2. Amend Sec. 136.3 as follows:
0
a. Revise tables IA, IB, IC, ID, and IH in paragraph (a);
0
b. Revise the introductory text to paragraph (b) and paragraphs
(b)(8)(ii) through (v), (b)(10)(i), (viii) through (xiv), (xvi) through
(xxvi), (xxviii) through (xxxv), (xxxvii), (xxxix) through (li), (lv)
through (lxiii), and (lxvii), (b)(15)(xi), (xx), (xxx), (xxxii), (lix),
(lxv) through (lxvii), and (lxix);
0
c. Redesignate paragraphs (b)(33) through (39) as paragraphs (b)(35)
through (41);
0
d. Add new paragraphs (b)(33) and (34); and
0
e. In paragraph (e), table II, revise Footnote ``5''.
The revisions and additions read as follows:

Sec. 136.3 Identification of test procedures.

* * * * *

Table IA--List of Approved Biological Methods for Wastewater and Sewage Sludge
--------------------------------------------------------------------------------------------------------------------------------------------------------
Parameter and units Method \1\ EPA Standard methods AOAC, ASTM, USGS Other
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bacteria
--------------------------------------------------------------------------------------------------------------------------------------------------------
1. Coliform (fecal), number per Most Probable p. 132; \3\ 1680; 9221 E-2014........
gram dry weight. Number (MPN), 5 \11\ \15\ 1681
tube, 3 dilution, \11\ \20\.
or
Membrane filter p. 124 \3\......... 9222 D-2015 \29\...
(MF),\2\ \5\
single step.
2. Coliform (fecal), number per MPN, 5 tube, 3 p. 132 \3\......... 9221 E-2014; 9221 F-
100 mL. dilution, or. 2014 \33\.
Multiple tube/ ................... ................... ........................ Colilert-18[supreg].\13\ \18\
multiple well, or. \28\
MF,\2\ \5\ single p. 124 \3\......... 9222 D-2015 \29\... B-0050-85 \4\...........
step \5\.
3. Coliform (total), number per MPN, 5 tube, 3 p. 114 \3\......... 9221 B-2014........
100 mL. dilution, or.
MF,\2\ \5\ single p. 108 \3\......... 9222 B-2015 \30\... B-0025-85 \4\...........
step or.
MF,\2\ \5\ two step p. 111 \3\......... 9222 B-2015 \30\...
with enrichment.
4. E. coli, number per 100 mL... MPN \6\ \8\ \16\ ................... 9221 B2014/9221 F-
multiple tube, or. 2014 \12\ \14\
\33\.
multiple tube/ ................... 9223 B-2016 \13\... 991.15 \10\............. Colilert[supreg].\13\ \18\
multiple well, or. Colilert-18[supreg].\13\ \17\
\18\
MF,\2\ \5\ \6\ \7\ ................... 9222 B-2015/9222 I-
\8\ two step, or. 2015 \31\.
Single step........ 1603.1 \21\........ ................... ........................ m-ColiBlue24[supreg].\19\
5. Fecal streptococci, number MPN, 5 tube, 3 p. 139 \3\......... 9230 B-2013........
per 100 mL. dilution, or.
MF,\2\ or.......... p. 136 \3\......... 9230 C-2013 \32\... B-0055-85 \4\...........
Plate count........ p. 143 \3\.........
6. Enterococci, number per 100 MPN, 5 tube, 3 p. 139 \3\......... 9230 B-2013........
mL. dilution, or.

[[Page 10742]]

MPN,\6\ \8\ ................... 9230 D-2013........ D6503-99 \9\............ Enterolert[supreg].\13\ \23\
multiple tube/
multiple well, or.
MF \2\ \5\ \6\ \7\ 1600.1 \24\........ 9230 C-2013 \32\...
\8\ single step or.
Plate count........ p. 143 \3\.........
7. Salmonella, number per gram MPN multiple tube.. 1682 \22\..........
dry weight \11\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Aquatic Toxicity
--------------------------------------------------------------------------------------------------------------------------------------------------------
8. Toxicity, acute, fresh water Water flea, 2002.0 \25\........
organisms, LC50, percent Cladoceran,
effluent. Ceriodaphnia dubia
acute.
Water fleas, 2021.0 \25\........
Cladocerans,
Daphnia pulex and
Daphnia magna
acute.
Fish, Fathead 2000.0 \25\........
minnow, Pimephales
promelas, and
Bannerfin shiner,
Cyprinella leedsi,
acute.
Fish, Rainbow 2019.0 \25\........
trout,
Oncorhynchus
mykiss, and brook
trout, Salvelinus
fontinalis, acute.
9. Toxicity, acute, estuarine Mysid, Mysidopsis 2007.0 \25\.
and marine organisms of the bahia, acute. ...................
Atlantic Ocean and Gulf of Fish, Sheepshead 2004.0 \25\........
Mexico, LC50, percent effluent. minnow, Cyprinodon
variegatus, acute.
Fish, Silverside, 2006.0 \25\........
Menidia beryllina,
Menidia menidia,
and Menidia
peninsulae, acute.
10. Toxicity, chronic, fresh Fish, Fathead 1000.0 \26\........
water organisms, NOEC or IC25, minnow, Pimephales
percent effluent. promelas, larval
survival and
growth.
Fish, Fathead 1001.0 \26\........
minnow, Pimephales
promelas, embryo-
larval survival
and teratogenicity.
Water flea, 1002.0 \26\........
Cladoceran,
Ceriodaphnia
dubia, survival
and reproduction.
Green alga, 1003.0 \26\........
Selenastrum
capricornutum,
growth.
11. Toxicity, chronic, estuarine Fish, Sheepshead 1004.0 \27\........
and marine organisms of the minnow, Cyprinodon
Atlantic Ocean and Gulf of variegatus, larval
Mexico, NOEC or IC25, percent survival and
effluent. growth.

[[Page 10743]]

Fish, Sheepshead 1005.0 \27\........
minnow, Cyprinodon
variegatus, embryo-
larval survival
and teratogenicity.
Fish, Inland 1006.0 \27\........
silverside,
Menidia beryllina,
larval survival
and growth.
Mysid, Mysidopsis 1007.0 \27\........
bahia, survival,
growth, and
fecundity.
Sea urchin, Arbacia 1008.0 \27\........
punctulata,
fertilization.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table IA notes:
\1\ The method must be specified when results are reported.
\2\ A 0.45-[mu]m membrane filter (MF) or other pore size certified by the manufacturer to fully retain organisms to be cultivated and to be free of
extractables which could interfere with their growth.
\3\ Microbiological Methods for Monitoring the Environment, Water and Wastes, EPA/600/8-78/017. 1978. U.S. EPA.
\4\ U.S. Geological Survey Techniques of Water-Resource Investigations, Book 5, Laboratory Analysis, Chapter A4, Methods for Collection and Analysis of
Aquatic Biological and Microbiological Samples. 1989. USGS.
\5\ Because the MF technique usually yields low and variable recovery from chlorinated wastewaters, the Most Probable Number method will be required to
resolve any controversies.
\6\ Tests must be conducted to provide organism enumeration (density). Select the appropriate configuration of tubes/filtrations and dilutions/volumes
to account for the quality, character, consistency, and anticipated organism density of the water sample.
\7\ When the MF method has been used previously to test waters with high turbidity, large numbers of noncoliform bacteria, or samples that may contain
organisms stressed by chlorine, a parallel test should be conducted with a multiple-tube technique to demonstrate applicability and comparability of
results.
\8\ To assess the comparability of results obtained with individual methods, it is suggested that side-by-side tests be conducted across seasons of the
year with the water samples routinely tested in accordance with the most current Standard Methods for the Examination of Water and Wastewater or EPA
alternate test procedure (ATP) guidelines.
\9\ Annual Book of ASTM Standards-Water and Environmental Technology, Section 11.02. 2000, 1999, 1996. ASTM International.
\10\ Official Methods of Analysis of AOAC International. 16th Edition, 4th Revision, 1998. AOAC International.
\11\ Recommended for enumeration of target organism in sewage sludge.
\12\ The multiple-tube fermentation test is used in 9221B.2-2014. Lactose broth may be used in lieu of lauryl tryptose broth (LTB), if at least 25
parallel tests are conducted between this broth and LTB using the water samples normally tested, and this comparison demonstrates that the false-
positive rate and false-negative rate for total coliform using lactose broth is less than 10 percent. No requirement exists to run the completed phase
on 10 percent of all total coliform-positive tubes on a seasonal basis.
\13\ These tests are collectively known as defined enzyme substrate tests.
\14\ After prior enrichment in a presumptive medium for total coliform using 9221B.2-2014, all presumptive tubes or bottles showing any amount of gas,
growth or acidity within 48 h <plus-minus> 3 h of incubation shall be submitted to 9221F-2014. Commercially available EC-MUG media or EC media
supplemented in the laboratory with 50 [mu]g/mL of MUG may be used.
\15\ Method 1680: Fecal Coliforms in Sewage Sludge (Biosolids) by Multiple-Tube Fermentation Using Lauryl-Tryptose Broth (LTB) and EC Medium, EPA-821-R-
14-009. September 2014. U.S. EPA.
\16\ Samples shall be enumerated by the multiple-tube or multiple-well procedure. Using multiple-tube procedures, employ an appropriate tube and
dilution configuration of the sample as needed and report the Most Probable Number (MPN). Samples tested with Colilert[supreg] may be enumerated with
the multiple-well procedures, Quanti-Tray[supreg] or Quanti-Tray[supreg]/2000 and the MPN calculated from the table provided by the manufacturer.
\17\ Colilert-18[supreg] is an optimized formulation of the Colilert[supreg] for the determination of total coliforms and E. coli that provides results
within 18 h of incubation at 35[deg]C rather than the 24 h required for the Colilert[supreg] test and is recommended for marine water samples.
\18\ Descriptions of the Colilert[supreg], Colilert-18[supreg], Quanti-Tray[supreg], and Quanti-Tray[supreg]/2000 may be obtained from IDEXX
Laboratories, Inc.
\19\ A description of the mColiBlue24[supreg] test is available from Hach Company.
\20\ Method 1681: Fecal Coliforms in Sewage Sludge (Biosolids) by Multiple-Tube Fermentation Using A-1 Medium, EPA-821-R-06-013. July 2006. U.S. EPA.
\21\ Method 1603.1: Escherichia coli (E. coli) in Water by Membrane Filtration Using Modified Membrane-Thermotolerant Escherichia coli Agar (modified
mTEC), [in draft as of 2023]. U.S. EPA.
\22\ Method 1682: Salmonella in Sewage Sludge (Biosolids) by Modified Semisolid Rappaport-Vassiliadis (MSRV) Medium, EPA-821-R-14-012. September 2014.
U.S. EPA.
\23\ A description of the Enterolert[supreg] test may be obtained from IDEXX Laboratories Inc.
\24\ Method 1600.1: Enterococci in Water by Membrane Filtration Using Membrane-Enterococcus Indoxyl-[beta]-D-Glucoside Agar (mEI), [in draft as of
2023]. U.S. EPA.
\25\ Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, EPA-821-R-02-012. Fifth Edition,
October 2002. U.S. EPA; and U.S. EPA Whole Effluent Toxicity Methods Errata Sheet, EPA 821-R-02-012-ES. December 2016.
\26\ Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, EPA-821-R-02-013. Fourth Edition,
October 2002. U.S. EPA; and U.S. EPA Whole Effluent Toxicity Methods Errata Sheet, EPA 821-R-02-012-ES. December 2016.
\27\ Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms, EPA-821-R-02-014. Third
Edition, October 2002. U.S. EPA; and U.S. EPA Whole Effluent Toxicity Methods Errata Sheet, EPA 821-R-02-012-ES. December 2016.
\28\ To use Colilert-18[supreg] to assay for fecal coliforms, the incubation temperature is 44.5 <plus-minus> 0.2 [deg]C, and a water bath incubator is
used.
\29\ On a monthly basis, at least ten blue colonies from positive samples must be verified using Lauryl Tryptose Broth and EC broth, followed by count
adjustment based on these results; and representative non-blue colonies should be verified using Lauryl Tryptose Broth. Where possible, verifications
should be done from randomized sample sources.
\30\ On a monthly basis, at least ten sheen colonies from positive samples must be verified using lauryl tryptose broth and brilliant green lactose bile
broth, followed by count adjustment based on these results; and representative non-sheen colonies should be verified using lauryl tryptose broth.
Where possible, verifications should be done from randomized sample sources.

[[Page 10744]]

\31\ Subject coliform positive samples determined by 9222 B-2015 or other membrane filter procedure to 9222 I-2015 using NA-MUG media.
\32\ Verification of colonies by incubation of BHI agar at 10 <plus-minus> 0.5 [deg]C for 48 <plus-minus> 3 h is optional. As per the Errata to the 23rd
Edition of Standard Methods for the Examination of Water and Wastewater ``Growth on a BHI agar plate incubated at 10 <plus-minus> 0.5 [deg]C for 48
<plus-minus> 3 h is further verification that the colony belongs to the genus Enterococcus.''
\33\ 9221F. 2-2014 allows for simultaneous detection of E. coli and thermotolerant fecal coliforms by adding inverted vials to EC-MUG; the inverted
vials collect gas produced by thermotolerant fecal coliforms.

Table IB--List of Approved Inorganic Test Procedures
--------------------------------------------------------------------------------------------------------------------------------------------------------
Parameter Methodology \58\ EPA \52\ Standard methods \84\ ASTM USGS/AOAC/other
--------------------------------------------------------------------------------------------------------------------------------------------------------
1. Acidity, as CaCO3, mg/L......... Electrometric endpoint ...................... 2310 B-2020.......... D1067-16............. I-1020-85.\2\
or phenolphthalein
endpoint.
2. Alkalinity, as CaCO3, mg/L...... Electrometric or ...................... 2320 B-2021.......... D1067-16............. 973.43,\3\ I-1030-
Colorimetric 85.\2\
titration to pH 4.5,
Manual.
Automatic............. 310.2 (Rev. 1974) \1\. ..................... ..................... I-2030-85.\2\
3. Aluminum--Total, \4\ mg/L....... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 D-2019 or 3111 E- ..................... I-3051-85.\2\
\36\. 2019.
AA furnace............ ...................... 3113 B-2020..........
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev 4.2 3120 B-2020.......... D1976-20............. I-4471-97.\50\
(2003),\68\ 200.7,
Rev. 4.4 (1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
Direct Current Plasma ...................... ..................... D4190-15............. See footnote.\34\
(DCP) \36\.
Colorimetric ...................... 3500-Al B-2020.......
(Eriochrome cyanine
R).
4. Ammonia (as N), mg/L............ Manual distillation 350.1, Rev. 2.0 (1993) 4500-NH3 B-2021...... ..................... 973.49.\3\
\6\ or gas diffusion
(pH > 11), followed
by any of the
following:
Nesslerization........ ...................... ..................... D1426-15 (A)......... 973.49,\3\ I-3520-
85.\2\
Titration............. ...................... 4500-NH3 C-2021......
Electrode............. ...................... 4500-NH3 D-2021 or E- D1426-15 (B).........
2021.
Manual phenate, ...................... 4500-NH3 F-2021...... ..................... See footnote.\60\
salicylate, or other
substituted phenols
in Berthelot reaction-
based methods.
Automated phenate, 350.1,\30\ Rev. 2.0 4500-NH3 G-2021 4500- ..................... I-4523-85,\2\ I-2522-
salicylate, or other (1993). NH3 H-2021. 90.\80\
substituted phenols
in Berthelot reaction-
based methods.
Automated electrode... ...................... ..................... ..................... See footnote.\7\
Ion Chromatography.... ...................... ..................... D6919-17.............
Automated gas ...................... ..................... ..................... Timberline Ammonia-
diffusion, followed 001.\74\
by conductivity cell
analysis.
Automated gas ...................... ..................... ..................... FIAlab100.\82\
diffusion followed by
fluorescence detector
analysis.
5. Antimony--Total, \4\ mg/L....... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019..........
\36\.
AA furnace............ ...................... 3113 B-2020..........
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev 4.2 (2003); 3120 B-2020.......... D1976-20.............
\68\ 200.7, Rev. 4.4
(1994).

[[Page 10745]]

ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
6. Arsenic--Total,\4\ mg/L......... Digestion,\4\ followed 206.5 (Issued 1978)
by any of the \1\.
following:
AA gaseous hydride.... ...................... 3114 B-2020 or 3114 C- D2972-15 (B)......... I-3062-85.\2\
2020.
AA furnace............ ...................... 3113 B-2020.......... D2972-15 (C)......... I-4063-98.\49\
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev 4.2 (2003); 3120 B-2020.......... D1976-20.............
\68\ 200.7, Rev. 4.4
(1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4020-
05.\70\
Colorimetric (SDDC)... ...................... 3500-As B-2020....... D2972-15 (A)......... I-3060-85.\2\
7. Barium--Total,\4\ mg/L.......... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 D-2019.......... ..................... I-3084-85.\2\
\36\.
AA furnace............ ...................... 3113 B-2020.......... D4382-18.............
ICP/AES \36\.......... 200.5, Rev 4.2 (2003); 3120 B-2020.......... ..................... I-4471-97.\50\
\68\ 200.7, Rev. 4.4
(1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
DCP \36\.............. ...................... ..................... ..................... See footnote.\34\
8. Beryllium--Total,\4\ mg/L....... Digestion,\4\ followed
by any of the
following:
AA direct aspiration.. ...................... 3111 D-2019 or 3111 E- D3645-15 (A)......... I-3095-85.\2\
2019.
AA furnace............ ...................... 3113 B-2020.......... D3645-15 (B).........
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES............... 200.5, Rev 4.2 (2003); 3120 B-2020.......... D1976-20............. I-4471-97.\50\
\68\ 200.7, Rev. 4.4
(1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
DCP................... ...................... ..................... D4190-15............. See footnote.\34\
Colorimetric ...................... See footnote.\61\....
(aluminon).
9. Biochemical oxygen demand Dissolved Oxygen ...................... 5210 B-2016 \85\..... ..................... 973.44,\3\ p. 17,\9\
(BOD5), mg/L. Depletion. I-1578-78,\8\ See
footnote.\10\ \63\
10. Boron--Total,\37\ mg/L......... Colorimetric ...................... 4500-B B-2011........ ..................... I-3112-85.\2\
(curcumin).
ICP/AES............... 200.5, Rev 4.2 (2003); 3120 B-2020.......... D1976-20............. I-4471-97.\50\
\68\ 200.7, Rev. 4.4
(1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14.\3\
DCP................... ...................... ..................... D4190-15............. See footnote.\34\
11. Bromide, mg/L.................. Electrode............. ...................... ..................... D1246-16............. I-1125-85.\2\
Ion Chromatography.... 300.0, Rev 2.1 (1993) 4110 B-2020, C-2020 D4327-17............. 993.30,\3\ I-2057-
and 300.1, Rev 1.0 or D-2020. 85.\79\
(1997).
CIE/UV................ ...................... 4140 B-2020.......... D6508-15............. D6508, Rev. 2.\54\
12. Cadmium--Total,\4\ mg/L........ Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019 or 3111 C- D3557-17 (A or B).... 974.27,\3\ p. 37,\9\
\36\. 2019. I-3135-85 \2\ or I-
3136-85.\2\
AA furnace............ ...................... 3113 B-2020.......... D3557-17 (D)......... I-4138-89.\51\
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev 4.2 (2003); 3120 B-2020.......... D1976-20............. I-1472-85 \2\ or I-
\68\ 200.7, Rev. 4.4 4471-97.\50\
(1994).

[[Page 10746]]

ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
DCP \36\.............. ...................... ..................... D4190-15............. See footnote.\34\
Voltammetry \11\...... ...................... ..................... D3557-17 (C).........
Colorimetric ...................... 3500-Cd-D-1990.......
(Dithizone).
13. Calcium--Total,\4\ mg/L........ Digestion,\4\ followed
by any of the
following:
AA direct aspiration.. ...................... 3111 B-2019 or 3111 D- D511-14 (B).......... I-3152-85.\2\
2019.
ICP/AES............... 200.5, Rev 4.2 (2003); 3120 B-2020.......... ..................... I-4471-97.\50\
\68\ 200.7, Rev. 4.4
(1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14.\3\
DCP................... ...................... ..................... ..................... See footnote.\34\
Titrimetric (EDTA).... ...................... 3500-Ca B-2020....... D511-14 (A)..........
Ion Chromatography.... ...................... ..................... D6919-17.............
14. Carbonaceous biochemical oxygen Dissolved Oxygen ...................... 5210 B-2016 \85\..... ..................... See footnote.\35\
demand (CBOD5), mg/L \12\. Depletion with \63\
nitrification
inhibitor.
15. Chemical oxygen demand (COD), Titrimetric........... 410.3 (Rev. 1978) \1\. 5220 B-2011 or C-2011 D1252-06(12) (A)..... 973.46,\3\ p. 17,\9\
mg/L. I-3560-85.\2\
Spectrophotometric, 410.4, Rev. 2.0 (1993) 5220 D-2011.......... D1252-06(12) (B)..... See footnotes,\13\
manual or automatic. \14\ \83\ I-3561-
85.\2\
16. Chloride, mg/L................. Titrimetric: (silver ...................... 4500-Cl- B-2021...... D512-12 (B).......... I-1183-85.\2\
nitrate).
(Mercuric nitrate).... ...................... 4500-Cl- C-2021...... D512-12 (A).......... 973.51,\3\ I-1184-
85.\2\
Colorimetric: manual.. ...................... ..................... ..................... I-1187-85.\2\
Automated ...................... 4500-Cl- E-2021...... ..................... I-2187-85.\2\
(ferricyanide).
Potentiometric ...................... 4500-Cl- D-2021......
Titration.
Ion Selective ...................... ..................... D512-12 (C)..........
Electrode.
Ion Chromatography.... 300.0, Rev 2.1 (1993) 4110 B-2020 or 4110 C- D4327-17............. 993.30,\3\ I-2057-
and 300.1, Rev 1.0 2020. 90.\51\
(1997).
CIE/UV................ ...................... 4140 B-2020.......... D6508-15............. D6508, Rev. 2.\54\
17. Chlorine--Total residual, mg/L. Amperometric direct... ...................... 4500-Cl D-2011....... D1253-14.............
Amperometric direct ...................... 4500-Cl E-2011.......
(low level).
Iodometric direct..... ...................... 4500-Cl B-2011.......
Back titration ether ...................... 4500-Cl C-2011.......
end-point \15\.
DPD-FAS............... ...................... 4500 Cl F-2011.......
Spectrophotometric, ...................... 4500-Cl G-2011.......
DPD.
Electrode............. ...................... ..................... ..................... See footnote.\16\
17A. Chlorine-Free Available, mg/L. Amperometric direct... ...................... 4500-Cl D-2011....... D1253-14.............
Amperometric direct ...................... 4500-Cl E-2011.......
(low level).
DPD-FAS............... ...................... 4500-Cl F-2011.......
Spectrophotometric, ...................... 4500-Cl G-2011.......
DPD.
18. Chromium VI dissolved, mg/L.... 0.45-micron filtration
followed by any of
the following:
AA chelation- ...................... 3111 C-2019.......... ..................... I-1232-85.\2\
extraction.
Ion Chromatography.... 218.6, Rev. 3.3 (1994) 3500-Cr C-2020....... D5257-17............. 993.23.\3\
Colorimetric (diphenyl- ...................... 3500-Cr B-2020....... D1687-17 (A)......... I-1230-85.\2\
carbazide).

[[Page 10747]]

19. Chromium--Total,\4\ mg/L....... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019.......... D1687-17 (B)......... 974.27,\3\ I-3236-
\36\. 85.\2\
AA chelation- ...................... 3111 C-2019..........
extraction.
AA furnace............ ...................... 3113 B-2020.......... D1687-17 (C)......... I-3233-93.\46\
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev 4.2 3120 B-2020.......... D1976-20.............
(2003),\68\ 200.7,
Rev. 4.4 (1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4020-05
\70\ I-4472-97.\81\
DCP \36\.............. ...................... ..................... D4190-15............. See footnote.\34\
Colorimetric (diphenyl- ...................... 3500-Cr B-2020.......
carbazide).
20. Cobalt--Total,\4\ mg/L......... Digestion,\4\ followed
by any of the
following:
AA direct aspiration.. ...................... 3111 B-2019 or 3111 C- D3558-15 (A or B).... p. 37,\9\ I-3239-
2019. 85.\2\
AA furnace............ ...................... 3113 B-2020.......... D3558-15 (C)......... I-4243-89.\51\
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES............... 200.7, Rev. 4.4 (1994) 3120 B-2020.......... D1976-20............. I-4471-97.\50\
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4020-05
\70\ I-4472-97.\81\
DCP................... ...................... ..................... D4190-15............. See footnote.\34\
21. Color, platinum cobalt units or Colorimetric (ADMI)... ...................... 2120 F-2021 \78\.....
dominant wavelength, hue,
luminance purity.
Platinum cobalt visual ...................... 2120 B-2021.......... ..................... I-1250-85.\2\
comparison.
Spectrophotometric.... ...................... ..................... ..................... See footnote.\18\
22. Copper--Total,\4\ mg/L......... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019 or 3111 C- D1688-17 (A or B).... 974.27,\3\ p. 37,\9\
\36\. 2019. I-3270-85 \2\ or I-
3271-85.\2\
AA furnace............ ...................... 3113 B-2020.......... D1688-17 (C)......... I-4274-89.\51\
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev 4.2 (2003); 3120 B-2020.......... D1976-20............. I-4471-97.\50\
\68\ 200.7, Rev. 4.4
(1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4020-
05,\70\ I-4472-
97.\81\
DCP \36\.............. ...................... ..................... D4190-15............. See footnote.\34\
Colorimetric ...................... 3500-Cu B-2020.......
(Neocuproine).
Colorimetric ...................... 3500-Cu C-2020....... ..................... See footnote.\19\
(Bathocuproine).
23. Cyanide--Total, mg/L........... Automated UV digestion/ ...................... ..................... ..................... Kelada-01.\55\
distillation and
Colorimetry.
Segmented Flow ...................... 4500-CN- P-2021...... D7511-12(17).........
Injection, In-Line
Ultraviolet
Digestion, followed
by gas diffusion
amperometry.
Manual distillation 335.4, Rev. 1.0 (1993) 4500-CN- B-2021 and C- D2036-09(15)(A), 10-204-00-1-X.\56\
with MgCl2, followed \57\. 2021. D7284-20.
by any of the
following:
Flow Injection, gas ...................... ..................... D2036-09(15)(A) D7284-
diffusion amperometry. 20.

[[Page 10748]]

Titrimetric........... ...................... 4500-CN- D-2021...... D2036-09(15)(A)...... p. 22.\9\
Spectrophotometric, ...................... 4500-CN- E-2021...... D2036-09(15)(A)...... I-3300-85.\2\
manual.
Semi-Automated \20\... 335.4, Rev. 1.0 (1993) 4500-CN- N-2021...... ..................... 10-204-00-1-X,\56\ I-
\57\. 4302-85.\2\
Ion Chromatography.... ...................... ..................... D2036-09(15)(A)......
Ion Selective ...................... 4500-CN- F-2021...... D2036-09(15)(A)......
Electrode.
24. Cyanide-Available, mg/L........ Cyanide Amenable to ...................... 4500-CN- G-2021...... D2036-09(15)(B)......
Chlorination (CATC);
Manual distillation
with MgCl2, followed
by Titrimetric or
Spectrophotometric.
Flow injection and ...................... 4500-CN- Q-2021...... D6888-16............. OIA-1677-09.\44\
ligand exchange,
followed by gas
diffusion amperometry
\59\.
Automated Distillation ...................... ..................... ..................... Kelada-01.\55\
and Colorimetry (no
UV digestion).
24. A Cyanide-Free, mg/L........... Flow Injection, ...................... 4500-CN- R-2021...... D7237-18 (A)......... OIA-1677-09.\44\
followed by gas
diffusion amperometry.
Manual micro-diffusion ...................... ..................... D4282-15.............
and colorimetry.
25. Fluoride--Total, mg/L.......... Manual ...................... 4500-F- B-2021....... D1179-16 (A).........
distillation,\6\
followed by any of
the following:
Electrode, manual..... ...................... 4500-F- C-2021....... D1179-16 (B).........
Electrode, automated.. ...................... 4500-F- G-2021....... ..................... I-4327-85.\2\
Colorimetric, (SPADNS) ...................... 4500-F- D-2021.......
Automated complexone.. ...................... 4500-F- E-2021.......
Ion Chromatography.... 300.0, Rev 2.1 (1993) 4110 B-2020 or C-2020 D4327-17............. 993.30.\3\
and 300.1, Rev 1.0
(1997).
CIE/UV................ ...................... 4140 B-2020.......... D6508-15............. D6508, Rev. 2.\54\
26. Gold--Total,\4\ mg/L........... Digestion,\4\ followed
by any of the
following:
AA direct aspiration.. ...................... 3111 B-2019..........
AA furnace............ 231.2 (Issued 1978) 3113 B-2020..........
\1\.
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14.\3\
DCP................... ...................... ..................... ..................... See footnote.\34\
27. Hardness--Total, as CaCO3, mg/L Automated colorimetric 130.1 (Issued 1971)
\1\.
Titrimetric (EDTA).... ...................... 2340 C-2021.......... D1126-17............. 973.52B,\3\ I-1338-
85.\2\
Ca plus Mg as their ...................... 2340 B-2021..........
carbonates, by any
approved method for
Ca and Mg (See
Parameters 13 and
33), provided that
the sum of the lowest
point of quantitation
for Ca and Mg is
below the NPDES
permit requirement
for Hardness.
28. Hydrogen ion (pH), pH units.... Electrometric ...................... 4500-H\+\ B-2021..... D1293-18 (A or B).... 973.41,\3\ I-1586-
measurement. 85.\2\
Automated electrode... 150.2 (Dec. 1982) \1\. ..................... ..................... See footnote,\21\ I-
2587-85.\2\

[[Page 10749]]

29. Iridium--Total,\4\ mg/L........ Digestion,\4\ followed
by any of the
following:
AA direct aspiration.. ...................... 3111 B-2019..........
AA furnace............ 235.2 (Issued 1978)
\1\.
ICP/MS................ ...................... 3125 B-2020..........
30. Iron--Total,\4\ mg/L........... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019 or 3111 C- D1068-15 (A)......... 974.27,\3\ I-3381-
\36\. 2019. 85.\2\
AA furnace............ ...................... 3113 B-2020.......... D1068-15 (B).........
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev. 4.2 3120 B-2020.......... D1976-20............. I-4471-97.\50\
(2003); \68\ 200.7,
Rev. 4.4 (1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14.\3\
DCP \36\.............. ...................... ..................... D4190-15............. See footnote.\34\
Colorimetric ...................... 3500-Fe B-2011....... D1068-15 (C)......... See footnote.\22\
(Phenanthroline).
31. Kjeldahl Nitrogen \5\--Total, Manual digestion \20\ ...................... 4500-Norg B-2021 or C- D3590-17 (A)......... I-4515-91.\45\
(as N), mg/L. and distillation or 2021 and 4500-NH3 B-
gas diffusion, 2021.
followed by any of
the following:
Titration............. ...................... 4500-NH3 C-2021...... ..................... 973.48.\3\
Nesslerization........ ...................... ..................... D1426-15 (A).........
Electrode............. ...................... 4500-NH3 D-2021 or E- D1426-15 (B).........
2021.
Semi-automated phenate 350.1, Rev. 2.0 (1993) 4500-NH3 G-2021 or
4500-NH3 H-2021.
Manual phenate, ...................... 4500-NH3 F-2021...... ..................... See footnote.\60\
salicylate, or other
substituted phenols
in Berthelot reaction
based methods.
Automated gas ...................... ..................... ..................... Timberline Ammonia-
diffusion, followed 001.\74\
by conductivity cell
analysis.
Automated gas ...................... ..................... ..................... FIAlab 100.\82\
diffusion followed by
fluorescence detector
analysis.
Automated Methods for TKN that do not require manual distillation
Automated phenate, 351.1 (Rev. 1978) \1\. ..................... ..................... I-4551-78.\8\
salicylate, or other
substituted phenols
in Berthelot reaction-
based methods
colorimetric (auto
digestion and
distillation).
Semi-automated block 351.2, Rev. 2.0 (1993) 4500-Norg D-2021..... D3590-17 (B)......... I-4515-91.\45\
digestor colorimetric
(distillation not
required).
Block digester, ...................... ..................... ..................... See footnote.\39\
followed by Auto
distillation and
Titration.
Block digester, ...................... ..................... ..................... See footnote.\40\
followed by Auto
distillation and
Nesslerization.
Block Digester, ...................... ..................... ..................... See footnote.\41\
followed by Flow
injection gas
diffusion
(distillation not
required).

[[Page 10750]]

Digestion with ...................... ..................... ..................... Hach 10242.\76\
peroxdisulfate,
followed by
Spectrophotometric
(2,6-dimethyl phenol).
Digestion with ...................... ..................... ..................... NCASI TNTP
persulfate, followed W10900.\77\
by Colorimetric.
32. Lead--Total,\4\ mg/L........... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019 or 3111 C- D3559-15 (A or B).... 974.27,\3\ I-3399-
\36\. 2019. 85.\2\
AA furnace............ ...................... 3113 B-2020.......... D3559-15 (D)......... I-4403-89.\51\
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev. 4.2 3120 B-2020.......... D1976-20............. I-4471-97.\50\
(2003); \68\ 200.7,
Rev. 4.4 (1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
DCP \36\.............. ...................... ..................... D4190-15............. See footnote.\34\
Voltammetry \11\...... ...................... ..................... D3559-15 (C).........
Colorimetric ...................... 3500-Pb B-2020.......
(Dithizone).
33. Magnesium--Total,\4\ mg/L...... Digestion,\4\ followed
by any of the
following:
AA direct aspiration.. ...................... 3111 B-2019.......... D511-14 (B).......... 974.27,\3\ I-3447-
85.\2\
ICP/AES............... 200.5, Rev. 4.2 3120 B-2020.......... D1976-20............. I-4471-97.\50\
(2003); \68\ 200.7,
Rev. 4.4 (1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14.\3\
DCP................... ...................... ..................... ..................... See footnote.\34\
Ion Chromatography.... ...................... ..................... D6919-17.............
34. Manganese--Total,\4\ mg/L...... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019 or 3111 C- D858-17 (A or B)..... 974.27,\3\ I-3454-
\36\. 2019. 85.\2\
AA furnace............ ...................... 3113 B-2020.......... D858-17 (C)..........
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev. 4.2 3120 B-2020.......... D1976-20............. I-4471-97.\50\
(2003); \68\ 200.7,
Rev. 4.4 (1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
DCP \36\.............. ...................... ..................... D4190-15............. See footnote.\34\
Colorimetric ...................... 3500-Mn B-2020....... ..................... 920.203.\3\
(Persulfate).
Colorimetric ...................... ..................... ..................... See footnote.\23\
(Periodate).
35. Mercury--Total, mg/L........... Cold vapor, Manual.... 245.1, Rev. 3.0 (1994) 3112 B-2020.......... D3223-17............. 977.22,\3\ I-3462-
85.\2\
Cold vapor, Automated. 245.2 (Issued 1974)
\1\.
Cold vapor atomic 245.7 Rev. 2.0 (2005) ..................... ..................... I-4464-01.\71\
fluorescence \17\.
spectrometry (CVAFS).
Purge and Trap CVAFS.. 1631E \43\............
36. Molybdenum--Total,\4\ mg/L..... Digestion,\4\ followed
by any of the
following:
AA direct aspiration.. ...................... 3111 D-2019.......... ..................... I-3490-85.\2\
AA furnace............ ...................... 3113 B-2020.......... ..................... I-3492-96.\47\
ICP/AES............... 200.7, Rev. 4.4 (1994) 3120 B-2020.......... D1976-20............. I-4471-97.\50\

[[Page 10751]]

ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4472-
97.\81\
DCP................... ...................... ..................... ..................... See footnote.\34\
37. Nickel--Total,\4\ mg/L......... Digestion,\4\ followed
by any of the
following:
AA direct aspiration ...................... 3111 B-2019 or 3111 C- D1886-14 (A or B).... I-3499-85.\2\
\36\. 2019.
AA furnace............ ...................... 3113 B-2020.......... D1886-14 (C)......... I-4503-89.\51\
STGFAA................ 200.9, Rev. 2.2 (1994)
ICP/AES \36\.......... 200.5, Rev. 4.2 3120 B-2020.......... D1976-20............. I-4471-97.\50\
(2003); \68\ 200.7,
Rev. 4.4 (1994).
ICP/MS................ 200.8, Rev. 5.4 (1994) 3125 B-2020.......... D5673-16............. 993.14,\3\ I-4020-
05,\70\ I-4472-
97.\81\
DCP \36\.............. ...................... ..................... D4190-15............. See footnote.\34\
38. Nitrate (as N), mg/L........... Ion Chromatography.... 300.0, Rev. 2.1 (1993) 4110 B-2020 or C-2020 D4327-17............. 993.30.\3\
and 300.1, Rev. 1.0
(1997).
CIE/UV................ ...................... 4140 B-2020.......... D6508-15............. D6508, Rev. 2.\54\
Ion Selective ...................... 4500-NO3- D-2019.....
Electrode.
Colorimetric (Brucine 352.1 (Issued 1971) ..................... ..................... 973.50,\3\ 419D,\86\
sulfate). \1\. p. 28.\9\
Spectrophotometric ...................... ..................... ..................... Hach 10206.\75\

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