ASTM D4193-08(2013)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
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Designation: D4193 − 08 (Reapproved 2013)
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 June 2013.
1. Scope in Closed Conduits (Withdrawn 2003)
D1193Specification for Reagent Water
1.1 This test method covers the quantitative colorimetric
D2036Test Methods for Cyanides in Water
laboratory measurement of dissolved thiocyanate in water,
D2777Practice for Determination of Precision and Bias of
wastewater,andsalinewaterintherangefrom0.1to2.0mg/L.
Applicable Test Methods of Committee D19 on Water
For higher concentrations, use an aliquot from the diluted
D3370Practices for Sampling Water from Closed Conduits
sample.
D3856Guide for Management Systems in Laboratories
1.1.1 Validation—This test method was validated over the
Engaged in Analysis of Water
range of 0.07 to 1.42 mg/L. This test method was validated at
D4210Practice for Intralaboratory Quality Control Proce-
nine laboratories at four levels. This test method may be valid
dures and a Discussion on Reporting Low-Level Data
for reporting results down to lower levels as validated in
(Withdrawn 2002)
individual user laboratories.
D4841Practice for Estimation of Holding Time for Water
1.1.2 Application—This test method has been validated in
Samples Containing Organic and Inorganic Constituents
reagent water, Type II, in multiple laboratories and 7 natural
D5788Guide for Spiking Organics into Aqueous Samples
waters, 1 laboratory effluent, 1 steel mill effluent, and 2
D5789Practice for Writing Quality Control Specifications
dechlorinated and treated sanitary effluents in single laborato-
for Standard Test Methods for Organic Constituents
ries. It is the user’s responsibility to assure the validity of the
(Withdrawn 2002)
test method on any untested matrices.
D5847Practice for Writing Quality Control Specifications
1.2 The values stated in SI units are to be regarded as
for Standard Test Methods for Water Analysis
standard. No other units of measurement are included in this
D7237Test Method for Free Cyanide and Aquatic Free
standard.
CyanidewithFlowInjectionAnalysis(FIA)UtilizingGas
1.3 This standard does not purport to address all of the
Diffusion Separation and Amperometric Detection
safety concerns, if any, associated with its use. It is the D7365Practice for Sampling, Preservation and Mitigating
responsibility of the user of this standard to establish appro-
Interferences in Water Samples for Analysis of Cyanide
priate safety and health practices and determine the applica- E60Practice for Analysis of Metals, Ores, and Related
bility of regulatory limitations prior to use.Forspecifichazard
Materials by Spectrophotometry
statements, see Section 9. E275PracticeforDescribingandMeasuringPerformanceof
Ultraviolet and Visible Spectrophotometers
2. Referenced Documents
2 3. Terminology
2.1 ASTM Standards:
D1129Terminology Relating to Water 3.1 Definitions—For definitions of terms used in this test
D1192Guide for Equipment for Sampling Water and Steam method, refer to Terminology D1129.
4. Summary of Test Method
This test method is under the jurisdiction ofASTM Committee D19 on Water
4.1 This test method consists of thiocyanate reacting with
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor
ferric ions at a pH of<2to form a colored complex which is
Organic Substances in Water.
determined colorimetrically at 460 nm and adheres to Beer’s
CurrenteditionapprovedJune1,2013.PublishedJuly2013.Originallyapproved
in 1982. Last previous edition approved in 2008 as D4193–08. DOI: 10.1520/ Law.
D4193-08R13E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
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D4193 − 08 (2013)
4.2 Industrial wastes may be highly colored and contain 7. Apparatus
variousinterferingorganiccompoundswhichmustberemoved
7.1 Spectrophotometer or Filter Photometer, suitable for
by adsorption on macroreticular resin prior to analysis.
absorbance measurements at 460 nm and using a 5-cm cell.
Filter photometers and photometric practices used in this test
5. Significance and Use
method shall conform to Practice E60. Spectrophotometers
5.1 This test method is useful for analysis of many natural shall conform to Practice E275.
waters that contain thiocyanate from organic decomposition
7.2 Column—Chromatographic, glass, 12-mm inside diam-
products and waste water discharges. Some industrial wastes,
eter by 600-mm length, equipped with a reservoir and
such as those from the metallurgical processing of gold ores,
stopcock,ora50-mLburetwithaglasswoolplugandafunnel
steel industry, petroleum refining, and coal gasification, may
attached with a short piece of tubing.
contain significant concentrations of thiocyanate. Thiocyanate
per se is not recognized as a toxic chemical compound.
8. Reagents and Materials
However, when chlorinated, thiocyanate is converted to the
highly toxic and volatile cyanogen chloride at high pH.
8.1 Purity of Reagents—Reagent-grade chemicals shall be
Oxidation of thiocyanate may also release toxic hydrogen used in all tests. Unless otherwise indicated, it is intended that
cyanide.The user of the method is advised to perform holding
all reagents shall conform to the specifications of the Commit-
time studies in accordance with Practice D4841 whenever teeonAnalyticalReagentsoftheAmericanChemicalSociety.
oxidants are present in the samples.
8.2 Purity of Water—Unless otherwise indicated, references
5.1.1 For information on the impact of cyanogens and
towatershallbeunderstoodtomeanreagentwaterconforming
cyanide compounds, seeAppendix X1 of Test Method D2036.
to Specification D1193, Type I or II, and demonstrated to be
free of specific interference for the test being performed.
6. Interferences
8.3 Acetone.
6.1 Hexavalent chromium interference is removed by ad-
justing the pH to 2 with concentrated nitric acid and adding 8.4 Ferric Nitrate Solution (404 g/L)—Dissolve 404 g of
ferrous sulfate. Raising the pH to 8.5–9 with sodium ferricnitrate(Fe(NO ) ·9H O)inabout800mLofwater.Add
3 3 2
hydroxide precipitates Fe (III) and Cr (III) as the hydroxides, to this solution 80 mL of concentrated nitric acid. Mix and
which are removed by filtration. dilute to 1 L with water.
6.2 Reducing agents that reduce Fe (III) to Fe (II), thus
8.5 Hexane.
preventing formation of the ferric thiocyanate complex, are
8.6 Hydrogen Peroxide Solution—(H O ), 30%.
2 2
destroyed by a few drops of hydrogen peroxide.
8.7 Macroreticular Resin, 18- to 50-mesh or equivalent.
6.3 High concentrations of cyanide in proportion to the
concentration of thiocyanate will react with the iron to form
8.8 Methyl Alcohol.
colored complexes.
8.9 Nitric Acid—Concentrated HNO , sp gr 1.42.
6.4 Colored or interfering organic compounds must be
8.10 Nitric Acid (0.1 M)—Mix6.4mLofconcentratednitric
removedbyadsorptiononmacroreticularadsorptionresinprior
acid in about 800 mL of water. Dilute to 1 L with water and
to analysis.
mix.
NOTE 1—Examples of interfering compounds are fluoride, phosphate,
−
8.11 Thiocyanate Solution, Stock (1 mL=1.0 mg SCN )—
oxalate, arsenate, tartrate, borate, etc. which form complexes with iron.
Production of a red color with ferric ions is typical of phenols, enols, Dissolve 1.673 g of potassium thiocyanate (KSCN) in water
oximes, and acetates.
and dilute to 1 L.
6.5 Oxidation of thiocyanate may also react to form
8.12 Thiocyanate Solution, Standard (1 mL=0.01 mg
cyanides, resulting in low results. The user of the method is −1
SCN )—Dilute 10 mL of the stock thiocyanate solution to 1
advised to perform holding time studies in accordance with
L with water. Prepare fresh for each use. See 10.4.
Practice D4841 whenever oxidants are present in the samples.
8.13 Sodium Hydroxide Solution (4 g/L)—Dissolve4gof
6.6 Removal of sulfides for cyanide analysis preservation
NaOH in about 800 mL of water. Mix and dilute to 1 L with
may result in reaction of cyanide to form thiocyanate. Use a
water.
separatesampleforthiocyanateanalysisthantheonepreserved
for cyanide analysis.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
Spencer, R. R., Leenheer, J., and Marti, V. C., “Automated Colorimetric listed by the American Chemical Society, see Annual Standards for Laboratory
Determination of Thiocyanate, Thiosulfate, and Tetrathionate in Water,’’ AOAC Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
94th Annual Meeting, Washington, DC, 1980. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Newman,A.A. (ed.), Chemistry and Biochemistry of Thiocyanic Acid and Its 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 (2013)
NOTE 2—Some analytical methods prescribe the use of lead carbonate
9. Precautions
or lead acetate to precipitate sulfide; however, sulfide and cyanide can
9.1 Manysampleswillalsocontaincyanide.Becauseofthe
form thiocyanate in the presence of lead causing decreased cyanide
toxicity of cyanide, great care must be exercised in its
recoveries; therefore, lead carbonate and lead acetate should be avoided.
Methodsthatspecifytheadditionofbismuthnitratetotreatsulfideduring
handling. Acidification of cyanide solutions produces toxic
total cyanide distillations have been demonstrated by ASTM committee
hydrocyanic acid (HCN). All manipulations must be done in
D19.06 to be ineffective. (Warning—Cyanide can be converted into
the hood so that any HCN gas that might escape is safely
thiocyanate in the presence of sulfide at a high pH, causing high results.)
vented.
10.4 Thiocyanate is biodegradable. Samples that may con-
9.2 Residualsampleremainscouldbetoxic;theseshouldbe
tain bacteria should be preserved at pH <2 by the addition of
disposed of properly.
mineral acid and refrigerated.
11. Preparation of Apparatus
10. Sampling
11.1 Resin Column—Measure out sufficient resin to fill the
10.1 Collect the sample in accordance with Specification
column or columns into a beaker and add five times the resin
D1192 and Practices D3370.
volume of acetone. Stir for 1 h with gentle agitation.
10.2 Thiocyanate is stable in both the acid and alkaline pH
11.2 Pouroffthefinesandtheacetonefromthesettledresin
range.
and add five times the resin volume of hexane. Stir for 1 h.
10.3 Ifthesampleistobepreservedforcyanide,removethe
11.3 Pour off any fines that may be present and the hexane
sulfide before stabilization at a high pH in accordance with
from the settled resin and add five times the resin volume of
Practices D7365 as follows: Treat the sample immediately
methanol. Stir for 15 min.
using any or all of the following techniques as necessary,
followed by adjustment of the sample to pH 12–13 and
11.4 Pour off the methanol from the settled resin and add
refrigeration.
threetimestheresinvolumeofNaOHsolution(4g/L).Stirfor
10.3.1 Sulfide—Test for the presence of sulfide by placing a
15 min.
drop of sample on a lead acetate test strip that has been
11.5 Pour off the NaOH solution from the settled resin and
previously moistened with acetate buffer. If the test strip turns
add three times the resin volume of 0.1 M HNO . Stir for 15
black, sulfide is present (above 50 mg/L S2-) and treatment is
min.
necessary as described in Sections 10.3.1.1 or 10.3.1.2.Ifthe
11.6 Pour off the HNO solution from the settled resin and
testisnegativeandtherearenofurtherinterferencessuspected,
add three times the resin volume of reagent water. Stir for 15
adjust the pH to 12–13, refrigerate, and ship or transport to the
min. Decant the water from the settled resin and use this
laboratory.
purified resin to fill the column.
10.3.1.1 If the sample contains sulfide as indicated with a
lead acetate test strip or is known to contain sulfides that will
11.7 Attach the tip of the column to a source of reagent
interfere with the test method, dilute the sample with reagent
water, and displace the air from the column with water to the
water until the lead acetate test strip no longer indicates the
bottom of the reservoir (tip of the funnel if a buret is used).
presence of sulfide (<50 mg/L S2-) or until the interference is
11.8 Addtheresinslurrytothereservoir(funnel)andallow
no longer significant to the analytical test method. For
it to fill the column by displacing the water to approximately
example, add 200 mLof freshly collected sample into a bottle
400-mm depth. This procedure will give a uniform column
containing 800 mLof reagent water, then test for sulfide again
with the correct degree of packing.
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 11.9 When the resin has settled allow the water to drain to
laboratory.Ifthetestforsulfideisstillpositive,furtherdilution the top of the resin bed. At no time should the liquid level be
isrequired;however,becarefulnottooverdilutethesampleas below the top of the resin bed.
the detection limit will be elevated by this factor. In the
11.10 Add and drain five 5-mL increments of sample
aforementioned example, the dilution factor would be equal to
solution to the column. Fill the reservoir (funnel) with the
5 (total volume/sample volume). Clearly indicate the dilution
remaining (125 mL) solution and allow it to pass through the
volumes on the sample and chain-of-custody form so that the
column at a rate of 20 mL/min. Discard the first 50 mL of
laboratory can mathematically correct the result.
eluate.
10.3.1.2 Alternatively, sulfide can be removed by precipita-
11.11 Collect the next 50 mL of eluate in a clean, dry,
tion if free cyanide is the only form of cyanide to be measured
graduated cylinder. Use this portion for color developmen
...