ASTM D4193-08(2020)e1
(Test Method)Standard Test Method for Thiocyanate in Water
Standard Test Method for Thiocyanate in Water
SIGNIFICANCE AND USE
5.1 This test method is useful for analysis of many natural waters that contain thiocyanate from organic decomposition products and waste water discharges. Some industrial wastes, such as those from the metallurgical processing of gold ores, steel industry, petroleum refining, and coal gasification, may contain significant concentrations of thiocyanate. Thiocyanate per se is not recognized as a toxic chemical compound. However, when chlorinated, thiocyanate is converted to the highly toxic and volatile cyanogen chloride at high pH. Oxidation of thiocyanate may also release toxic hydrogen cyanide. The user of the method is advised to perform holding time studies in accordance with Practice D4841 whenever oxidants are present in the samples.
5.1.1 For information on the impact of cyanogens and cyanide compounds, see Appendix X1 of Test Methods D2036.
SCOPE
1.1 This test method covers the quantitative colorimetric laboratory measurement of dissolved thiocyanate in water, waste water, and saline water in the range from 0.1 to 2.0 mg/L. For higher concentrations, use an aliquot from the diluted sample.
1.1.1 Validation—This test method was validated over the range of 0.07 to 1.42 mg/L. This test method was validated at nine laboratories at four levels. This test method may be valid for reporting results down to lower levels as validated in individual user laboratories.
1.1.2 Application—This test method has been validated in reagent water, Type II, in multiple laboratories and 7 natural waters, 1 laboratory effluent, 1 steel mill effluent, and 2 dechlorinated and treated sanitary effluents in single laboratories. It is the user’s responsibility to assure the validity of the test method on any untested matrices.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 9.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in 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.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in 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.
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Designation: D4193 − 08 (Reapproved 2020)
Standard Test Method for
Thiocyanate in Water
This standard is issued under the fixed designation D4193; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Warning notes were editorially updated throughout in January 2020.
1. Scope 2. Referenced Documents
1.1 This test method covers the quantitative colorimetric 2.1 ASTM Standards:
laboratory measurement of dissolved thiocyanate in water, D1129Terminology Relating to Water
wastewater,andsalinewaterintherangefrom0.1to2.0mg/L. D1192Guide for Equipment for Sampling Water and Steam
For higher concentrations, use an aliquot from the diluted in Closed Conduits (Withdrawn 2003)
sample. D1193Specification for Reagent Water
1.1.1 Validation—This test method was validated over the D2036Test Methods for Cyanides in Water
range of 0.07 to 1.42 mg/L. This test method was validated at D2777Practice for Determination of Precision and Bias of
nine laboratories at four levels. This test method may be valid Applicable Test Methods of Committee D19 on Water
for reporting results down to lower levels as validated in D3370Practices for Sampling Water from Flowing Process
individual user laboratories. Streams
1.1.2 Application—This test method has been validated in D3856Guide for Management Systems in Laboratories
reagent water, Type II, in multiple laboratories and 7 natural Engaged in Analysis of Water
waters, 1 laboratory effluent, 1 steel mill effluent, and 2 D4210Practice for Intralaboratory Quality Control Proce-
dechlorinated and treated sanitary effluents in single laborato- dures and a Discussion on Reporting Low-Level Data
ries. It is the user’s responsibility to assure the validity of the (Withdrawn 2002)
test method on any untested matrices. D4841Practice for Estimation of Holding Time for Water
Samples Containing Organic and Inorganic Constituents
1.2 The values stated in SI units are to be regarded as
D5788Guide for Spiking Organics into Aqueous Samples
standard. No other units of measurement are included in this
D5789Practice for Writing Quality Control Specifications
standard.
for Standard Test Methods for Organic Constituents
1.3 This standard does not purport to address all of the
(Withdrawn 2002)
safety concerns, if any, associated with its use. It is the
D5847Practice for Writing Quality Control Specifications
responsibility of the user of this standard to establish appro-
for Standard Test Methods for Water Analysis
priate safety, health, and environmental practices and deter-
D7237Test Method for Free Cyanide and Aquatic Free
mine the applicability of regulatory limitations prior to use.
CyanidewithFlowInjectionAnalysis(FIA)UtilizingGas
For specific hazard statements, see Section 9.
Diffusion Separation and Amperometric Detection
1.4 This international standard was developed in accor-
D7365Practice for Sampling, Preservation and Mitigating
dance with internationally recognized principles on standard-
Interferences in Water Samples for Analysis of Cyanide
ization established in the Decision on Principles for the
E60Practice for Analysis of Metals, Ores, and Related
Development of International Standards, Guides and Recom-
Materials by Spectrophotometry
mendations issued by the World Trade Organization Technical
E275PracticeforDescribingandMeasuringPerformanceof
Barriers to Trade (TBT) Committee.
Ultraviolet and Visible Spectrophotometers
1 2
This test method is under the jurisdiction ofASTM Committee D19 on Water For referenced ASTM standards, visit the ASTM website, www.astm.org, or
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Organic Substances in Water. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Jan. 1, 2020. Published January 2020. Originally the ASTM website.
ɛ1 3
approved in 1982. Last previous edition approved in 2013 as D4193–08 (2013) . The last approved version of this historical standard is referenced on
DOI: 10.1520/D4193-08R20E01. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4193 − 08 (2020)
3. Terminology 6.5 Oxidation of thiocyanate may also react to form
cyanides, resulting in low results. The user of the method is
3.1 Definitions:
advised to perform holding time studies in accordance with
3.1.1 For definitions of terms used in this standard, refer to
Practice D4841 whenever oxidants are present in the samples.
Terminology D1129.
6.6 Removal of sulfides for cyanide analysis preservation
4. Summary of Test Method
may result in reaction of cyanide to form thiocyanate. Use a
separatesampleforthiocyanateanalysisthantheonepreserved
4.1 This test method consists of thiocyanate reacting with
ferric ions at a pH of <2 to form a colored complex which is for cyanide analysis.
determined colorimetrically at 460 nm and adheres to Beer’s
7. Apparatus
Law.
7.1 Spectrophotometer or Filter Photometer, suitable for
4.2 Industrial wastes may be highly colored and contain
absorbance measurements at 460 nm and using a 5-cm cell.
variousinterferingorganiccompoundswhichmustberemoved
Filter photometers and photometric practices used in this test
by adsorption on macroreticular resin prior to analysis.
method shall conform to Practice E60. Spectrophotometers
5. Significance and Use
shall conform to Practice E275.
5.1 This test method is useful for analysis of many natural
7.2 Column—Chromatographic, glass, 12-mm inside diam-
waters that contain thiocyanate from organic decomposition
eter by 600-mm length, equipped with a reservoir and
products and waste water discharges. Some industrial wastes,
stopcock,ora50-mLburetwithaglasswoolplugandafunnel
such as those from the metallurgical processing of gold ores,
attached with a short piece of tubing.
steel industry, petroleum refining, and coal gasification, may
contain significant concentrations of thiocyanate. Thiocyanate 8. Reagents and Materials
per se is not recognized as a toxic chemical compound.
8.1 Purity of Reagents—Reagent-grade chemicals shall be
However, when chlorinated, thiocyanate is converted to the
used in all tests. Unless otherwise indicated, it is intended that
highly toxic and volatile cyanogen chloride at high pH.
all reagents shall conform to the specifications of the Commit-
Oxidation of thiocyanate may also release toxic hydrogen 7
teeonAnalyticalReagentsoftheAmericanChemicalSociety.
cyanide.The user of the method is advised to perform holding
8.2 Purity of Water—Unless otherwise indicated, references
time studies in accordance with Practice D4841 whenever
towatershallbeunderstoodtomeanreagentwaterconforming
oxidants are present in the samples.
to Specification D1193, Type I or II, and demonstrated to be
5.1.1 For information on the impact of cyanogens and
free of specific interference for the test being performed.
cyanidecompounds,seeAppendixX1ofTestMethodsD2036.
8.3 Acetone.
6. Interferences
8.4 Ferric Nitrate Solution (404 g/L)—Dissolve 404 g of
6.1 Hexavalent chromium interference is removed by ad-
ferricnitrate(Fe(NO ) ·9H O)inabout800mLofwater.Add
3 3 2
justing the pH to 2 with concentrated nitric acid and adding
to this solution 80 mL of concentrated nitric acid. Mix and
ferroussulfate.RaisingthepHto8.5–9withsodiumhydroxide
dilute to 1 L with water.
precipitates Fe (III) and Cr (III) as the hydroxides, which are
8.5 Hexane.
removed by filtration.
8.6 Hydrogen Peroxide Solution—(H O ), 30%.
2 2
6.2 Reducing agents that reduce Fe (III) to Fe (II), thus
preventing formation of the ferric thiocyanate complex, are
8.7 Macroreticular Resin, 18- to 50-mesh or equivalent.
destroyed by a few drops of hydrogen peroxide.
8.8 Methyl Alcohol.
6.3 High concentrations of cyanide in proportion to the
8.9 Nitric Acid—Concentrated HNO , sp gr 1.42.
concentration of thiocyanate will react with the iron to form
8.10 Nitric Acid (0.1 M)—Mix6.4mLofconcentratednitric
colored complexes.
acid in about 800 mL of water. Dilute to 1 L with water and
6.4 Colored or interfering organic compounds must be
mix.
removedbyadsorptiononmacroreticularadsorptionresinprior
−
8.11 Thiocyanate Solution, Stock (1 mL=1.0 mg SCN )—
to analysis.
Dissolve 1.673 g of potassium thiocyanate (KSCN) in water
NOTE 1—Examples of interfering compounds are fluoride, phosphate,
and dilute to 1 L.
oxalate, arsenate, tartrate, borate, etc. which form complexes with iron.
Production of a red color with ferric ions is typical of phenols, enols,
oximes, and acetates.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
Spencer, R. R., Leenheer, J., and Marti, V. C., “Automated Colorimetric DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
DeterminationofThiocyanate,Thiosulfate,andTetrathionateinWater,”AOAC94th Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
Annual Meeting, Washington, DC, 1980. U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
Newman,A.A. (ed.), Chemistry and Biochemistry of Thiocyanic Acid and Its copeial Convention, Inc. (USPC), Rockville, MD.
Derivatives, Academic Press, New York, NY, 1975. For the development of this test method, Amberlite XAD-8 has been used.
Shriner, R. L., and Fuson, R. C., Identification of Organic Compounds, John Amberlite is a trademark of the Rohm and Haas Co., Independence Mall West,
Wiley & Sons, Inc., New York, NY, 1948. Philadelphia, PA 19105.
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D4193 − 08 (2020)
8.12 Thiocyanate Solution, Standard (1 mL=0.01 mg cadmium chloride for each ml of sample. Cap and shake the
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SCN )—Dilute10mLofthestockthiocyanatesolutionto1L container to mix. Allow the precipitate to settle and test the
with water. Prepare fresh for each use. See 10.4. sample with lead acetate paper for residual sulfide. If
necessary, add more cadmium chloride but avoid adding
8.13 Sodium Hydroxide Solution (4 g/L)—Dissolve4gof
excess. Finally filter through a 0.45-µm filter. Refrigerate, then
NaOH in about 800 mL of water. Mix and dilute to 1 L with
transport or ship the filtrate to the laboratory.
water.
NOTE 2—Some analytical methods prescribe the use of lead carbonate
9. Precautions
or lead acetate to precipitate sulfide; however, sulfide and cyanide can
form thiocyanate in the presence of lead causing decreased cyanide
9.1 Manysampleswillalsocontaincyanide.Becauseofthe
recoveries; therefore, lead carbonate and lead acetate should be avoided.
toxicity of cyanide, great care must be exercised in its
Methodsthatspecifytheadditionofbismuthnitratetotreatsulfideduring
handling. Acidification of cyanide solutions produces toxic total cyanide distillations have been demonstrated by ASTM committee
D19.06 to be ineffective.
hydrocyanic acid (HCN). All manipulations must be done in
the hood so that any HCN gas that might escape is safely (Warning—Cyanide can be converted into thiocyanate in
vented. the presence of sulfide at a high pH, causing high results.)
10.4 Thiocyanate is biodegradable. Samples that may con-
9.2 Residualsampleremainscouldbetoxic;theseshouldbe
disposed of properly. tain bacteria should be preserved at pH <2 by the addition of
mineral acid and refrigerated.
10. Sampling
11. Preparation of Apparatus
10.1 Collect the sample in accordance with Guide D1192
and Practices D3370.
11.1 Resin Column—Measure out sufficient resin to fill the
column or columns into a beaker and add five times the resin
10.2 Thiocyanate is stable in both the acid and alkaline pH
volume of acetone. Stir for 1 h with gentle agitation.
range.
11.2 Pouroffthefinesandtheacetonefromthesettledresin
10.3 Ifthesampleistobepreservedforcyanide,removethe
and add five times the resin volume of hexane. Stir for 1 h.
sulfide before stabilization at a high pH in accordance with
PracticeD7365asfollows:Treatthesampleimmediatelyusing
11.3 Pour off any fines that may be present and the hexane
anyorallofthefollowingtechniquesasnecessary,followedby
from the settled resin and add five times the resin volume of
adjustment of the sample to pH 12–13 and refrigeration.
methanol. Stir for 15 min.
10.3.1 Sulfide—Test for the presence of sulfide by placing a
11.4 Pour off the methanol from the settled resin and add
drop of sample on a lead acetate test strip that has been
threetimestheresinvolumeofNaOHsolution(4g/L).Stirfor
previously moistened with acetate buffer. If the test strip turns
15 min.
black, sulfide is present (above 50 mg/L S2-) and treatment is
11.5 Pour off the NaOH solution from the settled resin and
necessary as described in 10.3.1.1 or 10.3.1.2. If the test is
add three times the resin volume of 0.1 M HNO . Stir for 15
negative and there are no further interferences suspected, 3
min.
adjust the pH to 12–13, refrigerate, and ship or transport to the
laboratory.
11.6 Pour off the HNO solution from the settled resin and
10.3.1.1 If the sample contains sulfide as indicated with a
add three times the resin volume of reagent water. Stir for 15
lead acetate test strip or is known to contain sulfides that will
min. Decant the water from the settled resin and use this
interfere with the test method, dilute the sample with reagent
purified resin to fill the column.
water until the lead acetate test strip no longer indicates the
11.7 Attach the tip of the column to a source of reagent
presence of sulfide (<50 mg/L S2-) or until the interference is
water, and displace the air from the column with water to the
no longer significant to the analytical test method. For
bottom of the reservoir (tip of the funnel if a buret is used).
example, add 200 mLof freshly collected sample into a bottle
containing 800 mLof reagent water, then test for sulfide again 11.8 Addtheresinslurrytothereservoir(funnel)andallow
it to fill the column by displacing the water to approximately
as indicated in 10.3.1. If the test for sulfide is negative, adjust
the pH to 12–13, refrigerate, and ship or transport to the 400-mm depth. This procedure will give a uniform column
with the correct degree of packing.
laboratory.Ifthetestforsulfideisstillpositive,furtherdilution
isrequired;however,becarefulnottooverdilutethesampleas
11.9 When the resin has settled allow the water
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