United States
Environmental Protection
Agency
Cyanide Clarification of Free and Total
Cyanide Analysis for Safe Drinking Water
Act (SDWA) Compliance
Office of Water (MS-140) EPA 815-B-16-012 August 2016
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Address questions concerning this document to:
Judith A. Brisbin, Ph.D.
U.S. EPA, Office of Ground Water and Drinking Water,
Technical Support Center
26 W. Martin Luther King Dr.
Cincinnati, OH 45268
(513) 569-7883
brisbin.judv@epa.gov
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Chemical Phase RuleV 1
Certification/Accreditation 1
Preservation 2
Excerpt from Table in 40 CFR 141.23 (k)(2) 2
Water Treatment and Cyanide 2
PE Acceptance Limits 2
Excerpt from Table in 40 CFR 141.23 (k)(3)(ii) 2
Maximum Contaminant Level (MCL) 2
Excerpt from Table in 40 CFR 141.62 (b) 3
Methodology 3
Excerpt from Table in 40 CFR 141.23 (a)(4)(i) 3
Excerpt from Table in 40 CFR 141.23 (k)(l) 4
Excerpt from Table in Appendix A to Subpart Cof Part 141 5
Modified Methodologies and Methods for Total and Free Cyanide Table 6
Modified Table for Total Cyanide 7
Modified Table for Free Cyanide 8
Modified Table for Total Cyanide (clean version) 9
Modified Table for Free Cyanide (clean version) 10
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c • •
57 FR 31776-31849 Chemical Phase Rule V (Vol. 57, No. 138, July 17, 1992) - States the following: Total
cyanide methods are allowed for screening, the Maximum Contaminant Level (MCL)/Maximum
Contaminant Level Goal (MCLG) applies to free cyanide, the agency definition of "free" is amenable to
chlorination, and the MCL and MCLG is 0.2 ppm (mg/L).
• Cyanide is regulated as Free Cyanide (Table in 40 CFR 141.62(b) defines an MCL of 0.2 mg/L for
Cyanide (as free cyanide)), but Total Cyanide methods are allowed for screening. The Total
Cyanide screening methods are easier, faster and cheaper than the Free Cyanide methods.
o If the total cyanide is <0.2 mg CN"/L, you can report free cyanide as <0.2 mg/L;
o If the total cyanide is >0.2 mg CN"/L, determine free cyanide by an approved free
cyanide method.
• The Agency has regulated FREE CYANIDE as Cyanides Amenable to Chlorination, and set the MCL
based on Free Cyanide.
• Cyanides amenable to chlorination provides a conservative estimate of toxicity because, in
addition to free cyanide, it recovers some weak acid dissociable metal cyanide complexes that
may or may not actually release free cyanide in the environment.
Note: A good resource for definitions of cyanide terms can be found in ASTM D 6696-05.
" red nation
The methods for free and total cyanide are listed in Table 40 CFR 141.23 (k)(l). Only the approved
methods may be used:
Analysis for the following contaminants shall be conducted in accordance with the methods in
the following table, or the alternative methods listed in appendix A to subpart C of this part, or
their equivalent as determined by EPA...
Free and total cyanide are part of the National Primary Drinking Water Regulations (NPDWRs) and 40
CFR 141.23 is referenced in 40 CFR 141.28(a) stating that laboratories analyzing compliance samples
must be certified/accredited as follows:
For the purpose of determining compliance with §141.21 through 141.27, 141.30, 141.40,
141.74,141.89 and 141.402, samples may be considered only if they have been analyzed by a
laboratory certified by the State...
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Preservation
Excerpt from Table in 40 CFR 141.23 (k)(2)
Contaminant
Cyanide
Preservative1
4"C, NaOH
Container2
PorG
Time3
14 days
1 For cyanide determinations samples must be adjusted with sodium hydroxide to pH 12 at the time of collection. When
chilling is indicated the sample must be shipped and stored at 4 °C or less ...
2 P = plastic, hard or soft; G=glass, hard or soft.
3 In all cases samples should be analyzed as soon after collection as possible. Follow additional (if any) information on
preservation, containers or holding times that is specified in method.
Summary: Container: Plastic or Glass
Preservation: NaOH to pH 12
4°C
Holding Time: 14 days
Water Treatment and Cyanide
The oxidative effects of disinfection (chlorination and/or most of the alternatives like ozone, chlorine
dioxide, etc...) can chemically alter the sample matrix and these oxidants may react with regulated
contaminants. This isn't limited to contaminants like cyanide and glyphosate. Disinfection is an integral
component of treatment, primarily to control microbial contaminants, but regulated contaminants may
also be removed as a secondary benefit. Other forms of treatment like aeration or Granular Activated
Carbon (GAC) are specifically designed to remove regulated organic chemicals, and even though these
treatments are used, the Public Water System (PWS) must still monitor for those contaminants.
Contaminants like cyanide (and glyphosate) are no different. The statements in some methods regarding
disinfectant reactivity with certain contaminants are typically included in those methods to assist
laboratories and PWSs with interpreting data, not to grant any allowance to the PWS to forgo
monitoring because of the expectation that the contaminant will no longer be measured in the treated
water. For example, microbial monitoring must still occur on the finished water even though the source
water is treated with chlorine as a disinfectant.
PE Acceptance Limits
The Table in 40 CFR 141.23 (k)(3)(ii) (excerpt shown below) lists the Performance Evaluation (PE)
Acceptance Limit for Cyanide as ± 25% at >0.1 mg/L.
Excerpt from Table in 40 CFR 141.23 (k)(3)(ii)
Contaminant
Cyanide
Acceptance
± 25% at >0
Limit
lmg/L
Maximum Contaminant Level (MCL)
The Table in 40 CFR 141.62 (b) (excerpt shown below) lists a Maximum Contaminant Level (MCL) of 0.2
mg/L for Cyanide (as free Cyanide). Cyanide is therefore regulated as free cyanide.
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Excerpt from Table in 40 CFR 141.62 (b)
Contaminant
(13) Cyanide (as free Cyanide)
MCL (mg/L)
0.2
Methodology
Methodologies for Cyanide are shown in Tables in 40 CFR 141.23 (a)(4)(i), 40 CFR 141.23 (k)(l) and
Appendix A to Subpart C of Part 141. Excerpts from these Tables are shown below.
Excerpt from Table in 40 CFR 141.23 (a)(4)(i)
Contaminant
Cyanide
MCL (mg/L)
0.2
Methodology
Distillation, Spectrophotometric3
Distillation, Automated,
Spectrophotometric3
Distillation, Amenable,
Spectrophotometric4
Distillation, Selective Electrode34
UV, Distillation, Spectrophotometric9
Micro Distillation, Flow Injection,
Spectrophotometric3
Ligand Exchange with Amperometry4
Detection limit (mg/L)
0.02
0.005
0.02
0.05
0.0005
0.0006
0.0005
3 Screening method for total cyanides.
4 Measures "free" cyanides when distillation, digestion, or ligand exchange is omitted.
9 Measures total cyanides when UV-digestor [sic] is used, and "free" cyanides when UV-digestor [sic] is bypassed.
[Note: This table is primarily used in conjunction with Consumer Confidence Reports.]
The Table in 40 CFR 141.23 (a)(4)(i) has several footnotes that indicate:
• Screening methods for total cyanides have footnote 3.
• Free cyanide methods - with distillation, digestion or ligand exchange omitted - are indicated by
footnote 4.
• There is one methodology associated with both footnotes 3 and 4 so it can be used to measure
both free and total cyanides.
• UV, Distillation, Spectrophotometric, footnote 9, is also approved to measure free and total
cyanides. It measures total cyanides when the UV-digester is used and free cyanides when the
UV-digester is bypassed.
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Excerpt from Table in 40 CFR 141.23 (k)(l)
Contaminant
12. Cyanide
Methodology13
Manual Distillation
followed by
Spectrophotometric,
Amenable
Spectrophotometric
[sic] Manual
Spectrophotometric
[sic] Semi-automated
Selective Electrode
UV, Distillation,
Spectrophotometric
Micro Distillation, Flow
Injection,
Spectrophotometric
Ligand Exchange and
Amperometry21
EPA
335.4s
ASTM3
D2036-
98 A
D2036-
98 B
D2036-
98 A
D6888-
04
SM4
(18th,
19th
ed.)
4500-
CI\TC
4500-
CI\TG
4500-
CN-E
4500-
CI\TF
SM4
(20th
ed.)
4500-
CI\TC
4500-
CN-G
4500-
CN-E
4500-
CN-F
SM
Online22
4500-CN-
G-99
4500-CN-
E-99
4500-CN-
F-99
Other
I-3300-855
Kelada-
Ol17
QuikChem
10-204-
00-1-X18
OIA-1677,
DW20
3 Annual Book of ASTM Standards, ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428,
http://www.astm.org.; Annual Book of ASTM Standards 1994, Vols. 11.01 and 11.02; Annual Book of ASTM Standards
1996, Vols. 11.01 and 11.02; Annual Book of ASTM Standards 1999, Vols. 11.01 and 11.02; Annual Book of ASTM
Standards 2003, Vols. 11.01 and 11.02.
4 Standard Methods for the Examination of Water and Wastewater, American Public Health Association, 800 I Street
NW., Washington, DC 20001-3710; Standard Methods for the Examination of Water and Wastewater, 18th edition
(1992); Standard Methods for the Examination of Water and Wastewater, 19th edition (1995); Standard Methods for
the Examination of Water and Wastewater, 20th edition (1998).The following methods from this edition cannot be
used: 3111 B, 3111 D, 3113 B, and 3114 B.
5 U.S. Geological Survey, Federal Center, Box 25286, Denver, CO 80225-0425; Methods for Analysis by the U.S.
Geological Survey National Water Quality Laboratory—Determination of Inorganic and Organic Constituents in Water
and Fluvial Sediment, Open File Report 93-125,1993; Techniques of Water Resources Investigation of the U.S.
Geological Survey, Book 5, Chapter A-l, 3rd edition, 1989.
6 "Methods for the Determination of Inorganic Substances in Environmental Samples," EPA/600/R-93/100, August 1993.
Available as Technical Report PB94-120821 at National Technical Information Service (NTIS), 5301 Shawnee Road,
Alexandria, VA 22312. http://www.ntis.gov.
13
17The description for the Kelada-01 Method, "Kelada Automated Test Methods for Total Cyanide, Acid Dissociable
Cyanide, And Thiocyanate," Revision 1.2, August 2001, EPA # 821-B-01-009 for cyanide is available from the National
Technical Information Service (NTIS), PB 2001-108275, 5285 Port Royal Road, Springfield, VA 22161. The toll free
telephone number is 800-553-6847. Note: A 450-W UV lamp may be used in this method instead of the 550-W lamp
specified if it provides performance within the quality control (QC) acceptance criteria of the method in a given
instrument. Similarly, modified flow cell configurations and flow conditions may be used in the method, provided that
the QC acceptance criteria are met.
18The description for the QuikChem Method 10-204-00-1-X, "Digestion and distillation of total cyanide in drinking and
wastewaters using MICRO DIST and determination of cyanide by flow injection analysis," Revision 2.1, November 30,
2000, for cyanide is available from Lachat Instruments, 6645 W. Mill Rd., Milwaukee, Wl 53218. Telephone: 414-358-
4200.
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20Method OIA-1677, DW "Available Cyanide by Flow Injection, Ligand Exchange, and Amperometry," January 2004. EPA-
821-R-04-001, Available from ALPKEM, A Division of Ol Analytical, P.O. Box 9010, College Station, TX 77842-9010.
21Sulfide levels below those detected using lead acetate paper may produce positive method interferences. Test samples
using a more sensitive sulfide method to determine if a sulfide interference is present, and treat samples accordingly.
22Standard Methods Online, American Public Health Association, 800 I Street NW., Washington, DC 20001, available at
http://www.standardmethods.org. The year in which each method was approved by the Standard Methods Committee
is designated by the last two digits in the method number. The methods listed are the only online versions that may be
used.
Excerpt from Table in Appendix A to Subpart C of Part 141
Contaminant
Cyanide
Methodology
Manual Distillation
followed by
Spectrophotometric,
Amenable
Spectrophotometric
Manual
Selective Electrode
Headspace Gas
Chromatography/Mass
Spectrometry
EPA
method
SM
21st
edition1
4500-
CI\TG
4500-
CI\TE
4500-
CI\TF
SM
22nd
edition28
4500-
CI\TG
4500-
CI\TE
4500-
CI\TF
SM
online3
ASTM4
D2036-
06 A
D2036-
06 B
D2036-
06 A
Other
ME355.017
Standard Methods for the Examination of Water and Wastewater, 21st edition (2005). Available from American Public
Health Association, 800 I Street, NW., Washington, DC 20001-3710.
Standard Methods Online are available at http://www.standardmethods.org. The year in which each method was
approved by the Standard Methods Committee is designated by the last two digits in the method number. The
methods listed are the only online versions that may be used.
Available from ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 or http://astm.org.
The methods listed are the only alternative versions that may be used.
Method ME355.01, Revision 1.0. "Determination of Cyanide in Drinking Water by GC/MS Headspace," May 26, 2009.
Available at http://www.nemi.gov or from James Eaton, H & E Testing Laboratory, 221 State Street, Augusta, ME
04333. (207) 287-2727.
8Standard Methods for the Examination of Water and Wastewater, 22nd edition (2012). Available from American Public
Health Association, 800 I Street NW., Washington, DC 20001-3710.
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Matching up the Methodologies in the cyanide entry in the Table at 40 CFR 141.23(a)(4)(i) with the
methods in the cyanide entries in the Tables at 40 CFR 141.23 (k)(l) & Appendix A to Subpart C of Part
141, the methods approved for free cyanides, total cyanides, and/or both can be determined.
Modified Methodologies and Methods for Total and Free Cyanide Table
Contaminant
12. Cyanide
Methodology
Manual Distillation
followed by
Spectrophotometric,
Amenable
Spectrophotometric
Manual
Spectrophotometric
Semi-automated
Selective Electrode
UV, Distillation,
Spectrophotometric
Micro Distillation, Flow
Injection,
Spectrophotometric
Ligand Exchange and
Amperometry
Headspace Gas
Chromatography/Mass
Spectrometry
EPA
335.4
(Rev.
1.0)
ASTM
D2036-
98 A, -
06 A
D2036-
98 B,-
06 B
D2036-
98 A, -
06 A
D6888-
04
SM
(18th,
19th,
20th
ed.)
4500-
CATC
4500-
CN-G
4500-
CN~E
4500-
CI\TF
SM
(21st,
22nd
ed.)
4500-
CN-G
4500-
CN~ E
4500-
CI\TF
SM
Online
4500-
CN-G-
99
4500-
CN~ E-
99
4500-
CN-F-
99
Other
USGS 1-
3300-85
Kelada-01
(Rev. 1.2;
EPA821-B-
01-009)
QuikChem
10-204-00-
l-X(Rev.
2.1)
OIA-1677,
DW (EPA
821-R-04-
001)
ME355.01
(Rev. 1.0)
TOTAL
FREE
BOTH
Note: The Headspace GC/MS Method ME 355.01, Rev. 1.0 was approved through an expedited methods
approval action for the determination of free cyanide in Aug. 2009 (74 FR 38348).
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Separating the free and total methods results in the following modified Tables. Please note the following
for both Tables:
1. For the Cyanide methods referenced from Standard Methods, 4500-CN- Sections A. Introduction
and B. Preliminary Treatment of Samples are included by reference.
2. SM 4500-CN- C in the unapproved editions allowed the use of magnesium chloride (MgCI2) to
be optional, provided no supportive data in changing the chemistry, and thus were not
approved.
Modified Table for Total Cyanide
Methodology
Manual Distillation
followed by
Manual
Spectrophotometry
Manual Distillation
followed by Semi-
Automated
Spectrophotometry
Manual Distillation
followed by
Cyanide-Selective
Electrode
Automated UV
Distillation
followed by
Automated
Spectrophotometry
Micro Distillation,
Flow Injection,
followed by
Automated
Spectrophotometry
EPA
335.4
(Rev. 1.0)
ASTM
D2036-98 A, -06 A
SM (ed.)
4500-C/\TC(18th, 19th
& 20th)
+
4500-C/\TŁ(18th, 19th,
20th, 21st, 22nd, &-99
online)
4500-CATC(18th, 19th
& 20th)
+
4500-CN- F (18th, 19th,
20th, 21st, 22nd, &-99
online)
Other
USGS 1-3300-85
Kelada-01 (Rev.
1.2;EPA821-B-01-
009)
QuikChem 10-204-
00-1-X (Rev. 2.1)
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Modified Table for Free Cyanide
Methodology
Manual Distillation
followed by Manual
Spectrometry,
Cyanides Amenable to
Chlorination1 2
Manual Distillation
followed by Cyanide-
Selective Electrode2
Automated UV
Distillation followed by
Automated
Spectrophotometry3
Ligand Exchange and
Amperometry2
Headspace Gas
Chromatography/Mass
Spectrometry
EPA
ASTM
D2036-98 A, -06 A
+
D2036-98 B, -06 B
D6888-04
SM (ed.)
4500-CI\rG(18th, 19th,
20th, 21st, 22nd, &-99
online)
+
4500-CATC(18th, 19th
& 20th)
+
4500-CN- E (18th, 19th,
20th, 21st, 22nd, &-99
online)
4500-CN- F (18th, 19th,
20th, 21st, 22nd, &-99
online)
Other
Kelada-01 (Rev.
1.2;EPA821-B-01-
009)
OIA-1677, DW
(EPA 821-R-04-
001)
ME355.01 (Rev.
1.0)
1 To determine cyanides amenable to chlorination, distillation as described in Part C of the Standard Method is still
required. This requires analysis of two sample aliquots. The first aliquot is subjected to a chlorine treatment to
decompose the cyanides. The second aliquot has no chlorine treatment. Both aliquots are distilled followed by manual
Spectrometry. The difference between the cyanide concentrations found in the two samples is expressed as cyanides
amenable to chlorination.
2 Free cyanide omits the distillation, digestion or ligand exchange.
3 Measures "free" cyanides when UV-digestor is bypassed.
Clean versions of the modified Tables for Total and Free Cyanide are shown below.
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Modified Table for Total Cyanide (clean version]
Methodology
Manual Distillation
followed by Manual
Spectrophotometry
Manual Distillation
followed by Semi-
Automated
Spectrophotometry
Manual Distillation
followed by
Cyanide-Selective
Electrode
Automated UV
Distillation followed
by Automated
Spectrophotometry
Micro Distillation,
Flow Injection,
followed by
Automated
Spectrophotometry
EPA
335.4
(Rev.
1.0)
ASTM
D2036-98 A, -06 A
SM (ed.)
4500-CI\TC(18th, 19th &
20th)
+
4500-CN- E (18th, 19th,
20th, 21st, 22nd, &-99
online)
4500-CN- C (18th, 19th &
20th)
+
4500-CN- F (18th, 19th,
20th, 21st, 22nd, &-99
online)
Other
USGS 1-3300-85
Kelada-01 (Rev.
1.2;EPA821-B-
01-009)
QuikChem 10-
204-00-1-X (Rev.
2.1)
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Modified Table for Free Cyanide (clean version)
Methodology
Manual
Spectrometry,
Cyanides Amenable
to Chlorination1'2
Cyanide-Selective
Electrode2
Automated
Spectrophotometry3
Amperometry2
Headspace Gas
Chromatography/M
ass Spectrometry
EPA
ASTM
D2036-98 A, -06 A
D2036-98 B, -06 B
D6888-04
SM (ed.)
4500-CN- G (18th, 19th,
20th, 21st, 22nd, &-99
online)
4500-CN- C (18th, 19th &
20th)
4500-CN- E (18th, 19th,
20th, 21st, 22nd, &-99
online)
4500-CN- F (18th, 19th,
20th, 21st, 22nd, &-99
online)
Other
Kelada-01 (Rev.
1.2; EPA 821-B-
01-009)
OIA-1677, DW
(EPA821-R-04-
001)
ME355.01 (Rev.
1.0)
1 To determine cyanides amenable to chlorination distillation as described in Part C of the Standard Method is still
required. This requires analysis of two sample aliquots. The first aliquot is subjected to a chlorine treatment to
decompose the cyanides. The second aliquot has no chlorine treatment. Both aliquots are distilled followed by manual
Spectrometry. The difference between the cyanide concentrations found in the two samples is expressed as cyanides
amenable to chlorination.
2 Free cyanide omits the distillation, digestion or ligand exchange.
3 Measures "free" cyanides when UV-digestor is bypassed.
10
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