ASTM D7365-07
(Practice)Standard Practice for Sampling, Preservation and Mitigating Interferences in Water Samples for Analysis of Cyanide
Standard Practice for Sampling, Preservation and Mitigating Interferences in Water Samples for Analysis of Cyanide
SIGNIFICANCE AND USE
Cyanide is routinely analyzed in water samples, often to demonstrate regulatory compliance; however, improper sample collection or pretreatment can result in significant positive or negative bias potentially resulting in unnecessary permit violations or undetected cyanide releases into the environment.
SCOPE
1.1 This practice is applicable for the collection and preservation of water samples for the analysis of cyanide. This practice also addresses the mitigation of known interferences prior to the analysis of cyanide.
1.2 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 Test Methods D 2036, D 4282, D 4374, D 6888, D 6994, and D 7237. This practice can also be applied to other cyanide methods, for example, US EPA Method 335.4 and Standard Methods 4500-CN- C.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D7365–07
Standard Practice for
Sampling, Preservation and Mitigating Interferences in
Water Samples for Analysis of Cyanide
This standard is issued under the fixed designation D 7365; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 4282 Test Method for Determination of Free Cyanide in
Water and Wastewater by Microdiffusion
1.1 This practice is applicable for the collection and pres-
D 4374 Test Methods for Cyanides in Water—Automated
ervation of water samples for the analysis of cyanide. This
Methods for Total Cyanide, Weak Acid Dissociable Cya-
practice also addresses the mitigation of known interferences
nide, and Thiocyanate
prior to the analysis of cyanide.
D 4411 Guide for Sampling Fluvial Sediment in Motion
1.2 The sampling, preservation and mitigation of interfer-
D 4840 Guide for Sample Chain-of-Custody Procedures
ence procedures described in this practice are recommended
D 4841 Practice for Estimation of Holding Time for Water
for the analysis of total cyanide, available cyanide, weak acid
Samples Containing Organic and Inorganic Constituents
dissociable cyanide, and free cyanide byTest Methods D 2036,
D 6888 Test Method for Available Cyanide with Ligand
D 4282, D 4374, D 6888, D 6994, and D 7237. This practice
Displacement and Flow InjectionAnalysis (FIA) Utilizing
can also be applied to other cyanide methods, for example, US
-
Gas Diffusion Separation and Amperometric Detection
EPA Method 335.4 and Standard Methods 4500-CN C.
D 6994 Test Method for Determination of Metal Cyanide
1.3 The values stated in SI units are to be regarded as
Complexes in Wastewater, Surface Water, Groundwater
standard. No other units of measurement are included in this
and Drinking Water UsingAnion Exchange Chromatogra-
standard.
phy with UV Detection
1.4 This standard does not purport to address all of the
D 6696 Guide for Understanding Cyanide Species
safety concerns, if any, associated with its use. It is the
D 7237 Test Method for Aquatic Free Cyanide with Flow
responsibility of the user of this standard to establish appro-
Injection Analysis (FIA) Utilizing Gas Diffusion Separa-
priate safety and health practices and determine the applica-
tion and Amperometric Detection
bility of regulatory limitations prior to use.
2.2 U.S. EPA Methods:
2. Referenced Documents
EPA OIA-1677
EPA Method 335.2
2.1 ASTM Standards:
EPA Method 335.4
D 1129 Terminology Relating to Water
2.3 APHA Standard:
D 1193 Specification for Reagent Water
Standard Methods 4500-CN Methods C, D, E, F, G, and I
D 1293 Test Methods for pH of Water
2.4 USGS Methods:
D 2036 Test Methods for Cyanides in Water
USGS I-3300-85
D 3370 Practices for SamplingWater from Closed Conduits
USGS I-4302-85
D 3694 Practices for Preparation of Sample Containers and
for Preservation of Organic Constituents
3. Terminology
D 3856 Guide for Good Laboratory Practices in Laborato-
3.1 Definitions:
ries Engaged in Sampling and Analysis of Water
1 3
This practice is under the jurisdiction of ASTM Committee D19 on Water and Available from United States Environmental Protection Association (EPA),
is the direct responsibility of Subcommittee D19.06 on Methods for Analysis for Ariel Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460, www.ep-
Organic Substances in Water. a.gov.
Current edition approved Aug. 1, 2007. Published August 2007. Standard Methods for the Examination of Water and Wastewater, 21st edition
For referenced ASTM standards, visit the ASTM website, www.astm.org, or (2005),AmericanPublicHealthAssociation(APHA),800IStreet,NWWashington,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM DC 20001, www.apha.org.
Standards volume information, refer to the standard’s Document Summary page on Available from United States Geological Survey, 12201 Sunrise Valley Drive,
the ASTM website. Reston, VA, 20192, www.usgs.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7365–07
For definitions of terms used in this practice, refer to dilute to volume. Warning—This is an exothermic reaction
Terminology D 1129 and Guide D 6696. and the solution will become very hot while being prepared. It
3.2 In this practice, refrigeration shall designate storing the is recommended to place the solution in a water bath to cool.
sample between its freezing point and 6°C. 6.9 Hydrated Lime—Ca(OH) powder.
6.10 Cadmium chloride, CdCl .
4. Summary of Practice
6.11 Ethylenediamine (EDA)
4.1 Samples are collected in appropriate containers, miti-
6.12 Reducing Agents—Sodium thiosulfate (Na S O ),
2 2 3
gated for known interferences, and stabilized with sodium ascorbic acid, sodium arsenite (NaAsO ), or sodium borohy-
hydroxide prior to analysis.
dride (NaBH ).
6.13 Filter Paper or Syringe equipped with Leur-Lock
5. Significance and Use
Filters—Unless specified, 0.45 µm pore size.
5.1 Cyanide is routinely analyzed in water samples, often to 6.14 Acidification Reagents—Concentrated hydrochloric
demonstrateregulatorycompliance;however,impropersample
acid (HCl) or concentrated sulfuric acid (H SO ).
2 4
collection or pretreatment can result in significant positive or
6.15 Sample Bottles—See section 8.2 for further informa-
negative bias potentially resulting in unnecessary permit vio-
tion about sample bottles.
lations or undetected cyanide releases into the environment.
7. Hazards
6. Reagents and Materials
7.1 Warning—Because of the toxicity of cyanide, great
6.1 Purity of Reagents—Reagent grade chemicals shall be
care must be exercised in its handling.Acidification of cyanide
used in this practice. Unless otherwise indicated, it is intended
solutions produces toxic hydrocyanic acid (HCN). Adequate
that all reagents shall conform to the specifications of the
ventilation is necessary when handling cyanide solutions and a
Committee on Analytical Reagents of the American Chemical
fume hood should be utilized whenever possible.
Society, where such specifications are available. Other grades
7.2 Warning—Many of the reagents used in these test
may be used, provided it is first ascertained that the reagent is
methods are highly toxic. These reagents and their solutions
of sufficiently high purity to permit its use without lessening
must be disposed of properly.
the accuracy of the determination.
6.2 Purity of Water—Unless otherwise indicated, references
8. Procedure
to water shall be understood to mean reagent water that meets
8.1 Laboratory personnel and field samplers should follow
the purity specifications of Type I or Type II water, presented
the practices described in Guide D 3856. When sampling
in D 1193.
closed conduits such as process streams refer to Practice
6.3 Acetate Buffer—Dissolve 410 g of sodium acetate tri-
D 3370. When sampling fluvial sediment in motion or open
hydrate (NaC H O ·3H O) in 500 mL of water. Add glacial
2 3 2 2
channel flow refer to Guide D 4411. It is recommended to
acetic acid to yield a solution pH of 4.5, approximately 500
consult with the analytical laboratory prior to collecting
mL.
samples to ensure the proper sample volume, containers,
6.4 Lead Acetate Test Strips—Turns black in presence of
preservatives, etc., as these parameters may vary depending on
sulfides. Moisten the paper with acetate buffer prior to use.
the analytical methods used to measure the cyanide.
Lead acetate test strips have been shown to be sensitive to
2-
8.2 Sample Containers:
about 50 mg/L S .
8.2.1 Sample containers shall be made of materials that will
6.5 Potassium Iodide (KI) Starch Test Paper—Turns blue in
not contaminate the sample, cleaned thoroughly to remove all
presence of free chlorine. Commercial alternative test strips
extraneous surface contamination prior to use. Chemically
may be used if they are shown to be at least as sensitive as the
resistant glass containers are suitable as well as rigid or
KI starch test strips.
collapsible plastic containers made of polyethylene or polypro-
6.6 pH Indicator Test Strips—pH indicator test strips ca-
pylene.
pable of changing color at 0.5 pH units in the range of pH 10
8.2.2 Virgin commercially cleaned containers certified to be
to 14. More than one test strip may be necessary to cover this
free of contamination are recommended; otherwise, wash
range.
containers with soap or biodegradable detergent if required,
6.7 Sodium Hydroxide Solution (5 % wt/vol)—Ina1L
then dry by draining. For further information on sample
volumetric flask, dissolve 50 g NaOH in reagent water and
containers, see Practices D 3694.
dilute to volume.
8.2.3 Samples should be collected and stored in dark bottles
6.8 Sodium Hydroxide Solution (50 % wt/vol)—In a beaker,
to minimize exposure to ultraviolet radiation.
dissolve 50 g NaOH in reagent water not to exceed 100 mL
8.3 Sample Collection, Preservation, and Mitigation of
total volume, then transfer to a 100-mL volumetric flask and
Interferences:
8.3.1 Collect a sample volume that is sufficient to the
analytical method into a sample bottle described above. If the
Reagent Chemicals, American Chemical Society Specifications , American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
requiredsamplevolumeisnotspecified,usually1Lissufficient
listed by the American Chemical Society, see Analar Standards for Laboratory
for most analytical test methods, however, flow injection and
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
automated methods usually consume considerably less sample
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. volume than manual methods.
D7365–07
8.3.2 Certain sample matrices may require immediate required; however, be careful not to over dilute the sample as
analysis to avoid cyanide degradation due to interferences. the detection limit will be elevated by this factor. In the
While holding times are specified in this practice, it is aforementioned example, the dilution factor would be equal to
recommended to estimate the actual holding time for each 5 (total volume/sample volume). Clearly indicate the dilution
sample matrix as described in Practice D 4841.Aholding time volumes on the sample and chain-of-custody form so that the
study is required for any sample matrix showing evidence that laboratory can mathematically correct the result.
theholdingtimeislessthanpresentedinthispractice.Potential 8.3.6.2 Alternatively, sulfide can be removed by precipita-
interferences and their corresponding analytical methods are tion if free cyanide is the only form of cyanide to be measured
shown in Table 1. In the absence of interference, simple (for example, Test Method D 7237). For removal of sulfide by
cyanides such as HCN, KCN, and NaCN are determined precipitation, if the pH is less than pH 11, raise the pH to 11
readily by each of the determinative steps, however, to deter- with NaOH solution, and then add approximately 1 mg of
mine “total” cyanide, metal cyanide bonds must be broken and powdered cadmium chloride for each mL of sample. Cap and
cyanide separated to produce simple cyanide. In most total shake the container to mix. Allow the precipitate to settle and
cyanide methods, this is accomplished by distillation from acid test the sample with lead acetate paper for residual sulfide. If
solution. Although distillation is assumed to eliminate or at necessary, add more cadmium chloride but avoid adding
least minimize most interferences, the high temperature and excess. Finally, filter through a 0.45 µm filter. Refrigerate, then
strong acid solutions can potentially introduce significant transport or ship the filtrate to the laboratory.
positive or negative bias. Interferences for total cyanide by
NOTE 1—Some analytical methods prescribe the use of lead carbonate
distillation are listed in Tables 2 and 3. Interferences are also
or lead acetate to precipitate sulfide; however, sulfide and cyanide can
dependent on the determinative step, which are shown inTable
form thiocyanate in the presence of lead causing decreased cyanide
4. recoveries; therefore, lead carbonate and lead acetate should be avoided.
Methods that specify the addition of bismuth nitrate to treat sulfide during
8.3.3 There may be interferences that are not mitigated by
total cyanide distillations have been demonstrated byASTM Subcommit-
this procedure. Any removal or suppression of interference
tee D19.06 to be ineffective.
may be employed, provided the laboratory demonstrates that it
8.3.6.3 Samples known or suspected to contain sulfide
more accurately measures cyanide through quality control
shouldbeanalyzedwithananalyticaltestmethodthathasbeen
measures described in the analytical test method.Any removal
demonstrated to be free from sulfide interference. Test Method
technique not described in this practice or the analytical test
D 6888 employs sulfide mitigation that can effectively remove
method should be documented along with supporting data.
2-
up to 50 mg/L S without prior treatment and has a lower
8.3.4 If the sample can be analyzed within 48 h and sulfide
method detection limit compared to colorimetric methods to
is not present, adjust the pH to 12–13 with sodium hydroxide
compensate for any required dilutions specified in section
(for example, 5 % NaOH or 50 % NaOH). For aquatic free
8.3.6.1. To determine total cyanide, distill as described in Test
cyanidebyTestMethodD 7237,adjusttopH11asspecifiedin
Methods D 2036 Test Method A or equivalent method (for
the test method. Verify the pH of each sample with pH
example, MIDI distillation described in EPA 335.4) and
indicator test strips or byTest Methods D 1293. Refrigerate the
analyze the distillate by Test Method D 6888 with sulfide
sample and analyze within 48 h.
abatement described in the method instead of colorimetry.
8.3.5 Otherwise, to extend the holding time to 14 days and
Samples and distillates known or suspected to contain sulfide
mitigate interferences, treat the sample immediately using any
should be processed as quickly as possible to avoid cyanide
or all of the following techniques as necessary, followed by
degradation.
adjustment of the sample to pH 12–13 and refrigeration.
8.3.7 Sulfite, Thiosulfate, or Thiocyanate—Samples con-
8.3.6 Sulfide—Test for the presence of sulfide by placing a
taining sulfite or thiosulfate can result in low cyanide recov-
drop of sample on a lead acetate test strip that has been
eries when distilled. If thiocyanate is present, it can
...
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