1、Designation: D 4193 02Standard Test Method forThiocyanate in Water1This standard is issued under the fixed designation D 4193; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indic
2、ates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of dissolvedthiocyanate in water, waste water, and saline water in the rangefrom 0.1 to 2.0 mg/L. For higher concentrat
3、ions, use an aliquotfrom the diluted sample.1.2 This test method has been used successfully withreagent grade, natural, and treated sanitary effluent waters. It isthe users responsibility to assure the validity of the testmethod on any untested matrices.1.3 This standard does not purport to address
4、all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specifichazards, see Section 9.2. Referenced Documents2.
5、1 ASTM Standards:D 1129 Terminology Relating to Water2D 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits2D 1193 Specification for Reagent Water2D 2036 Test Methods for Cyanides in Water3D 3370 Practices for Sampling Water from Closed Con-duits2D 3856 Guide for Good Laboratory
6、Practices in Laborato-ries Engaged in Sampling and Analysis of Water2D 4210 Practice for Interlaboratory Quality Control Proce-dures and a Discussion on Reporting Low-Level Data2D 5788 Guide for Spiking Organics intoAqueous Samples3D 5789 Practice for Writing Quality Control Specificationsfor Standa
7、rd Test Methods for Organic Constituents3D 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3E60Practice for Molecular Absorption SpectrometricMethods for Chemical Analysis of Metals, Ores, andRelated Materials4E 275 Practice for Describing and Meas
8、uring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-eters53. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D 1129.4. Summary of Test Method4.1 Thiocyanate reacts with ferric ions at a pH of2toform a colored complex which is det
9、ermined colorimetricallyat 460 nm and adheres to Beers Law.4.2 Industrial wastes may be highly colored and containvarious interfering organic compounds which must be removedby adsorption on macroreticular resin6prior to analysis.5. Significance and Use5.1 Many natural waters contain thiocyanate from
10、 organicdecomposition products and waste water discharges. Someindustrial wastes, such as those from the steel industry,petroleum refining, and coal gasification, may contain signifi-cant concentrations of thiocyanate. Thiocyanate per se is notrecognized as a toxic chemical compound. However, whench
11、lorinated, thiocyanate is converted to the highly toxic andvolatile cyanogen chloride.5.1.1 For information on the impact of cyanogen com-pounds, see Appendix X1 of Test Method D 2036.6. Interferences6.1 Hexavalent chromium interference is removed by ad-justing the pH to 2 with concentrated nitric a
12、cid and addingferrous sulfate. Raising the pH to 8.5-9 with sodium hydroxide1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.06 on Methods forAnalysis forOrganic Substances in Water.Current edition approved July 10, 2002.
13、Published August 2002. Originallypublished as D 4193 82. Last previous edition D 4193 95.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 11.02.4Annual Book of ASTM Standards, Vol 03.05.5Annual Book of ASTM Standards, Vol 03.06.6Spencer, R. R., Leenheer, J., and Marti, V
14、. C., “Automated ColorimetricDetermination of Thiocyanate, Thiosulfate, and Tetrathionate in Water, AOAC94th Annual Meeting, Washington, DC, 1980.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.precipitates Fe (III) and Cr (III) as t
15、he hydroxides, which areremoved by filtration.6.2 Reducing agents that reduce Fe (III) to Fe (II), thuspreventing formation of the ferric thiocyanate complex, aredestroyed by a few drops of hydrogen peroxide.6.3 High concentrations of cyanide in proportion to theconcentration of thiocyanate will rea
16、ct with the iron to formcolored complexes.6.4 Colored or interfering organic compounds must beremoved by adsorption on macroreticular adsorption resin priorto analysis.NOTE 1Examples of interfering compounds are fluoride, phosphate,oxalate, arsenate, tartrate, borate, etc. which form complexes with
17、iron.7Production of a red color with ferric ions is typical of phenols, enols,oximes, and acetates.87. Apparatus7.1 Spectrophotometer or Filter Photometer, suitable forabsorbance measurements at 460 nm and using a 5-cm cell.Filter photometers and photometric practices used in this testmethod shall c
18、onform to Practice E60. Spectrophotometersshall conform to Practice E 275.7.2 ColumnChromatographic, glass, 12-mm inside diam-eter by 600-mm length, equipped with a reservoir and stop-cock, or a 50-mL buret with a glass wool plug and a funnelattached with a short piece of tubing.8. Reagents and Mate
19、rials8.1 Purity of ReagentsReagent-grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Soci-ety.98.2 Purity of WaterUnless otherwise indicated, ref
20、erencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type II.8.3 Acetone.8.4 Ferric Nitrate Solution (404 g/L)Dissolve 404 g offerric nitrate (Fe(NO3)39H2O) in about 800 mL of water.Addto this solution 80 mL of concentrated nitric acid. Mix anddilute to 1 L wi
21、th water.8.5 Hexane.8.6 Hydrogen Peroxide Solution(H2O2), 30 %.8.7 Macroreticular Resin10, 18- to 50-mesh or equivalent.8.8 Methyl Alcohol.8.9 Nitric AcidConcentrated HNO3, sp gr 1.42.8.10 Nitric Acid (0.1 M)Mix 6.4 mLof concentrated nitricacid in about 800 mL of water. Dilute to 1 L with water andm
22、ix.8.11 Thiocyanate Solution, Stock (1 mL = 1.0 mg SCN)Dissolve 1.673 g of potassium thiocyanate (KSCN) in waterand dilute to 1 L.8.12 Thiocyanate Solution, Standard (1 mL = 0.01 mgSCN1)Dilute 10 mL of the stock thiocyanate solution to 1L with water. Prepare fresh for each use. See 10.4.8.13 Sodium
23、Hydroxide Solution (4 g/L)Dissolve4gofNaOH in about 800 mL of water. Mix and dilute to 1 L withwater.9. Hazards9.1 Many samples will also contain cyanide. Because of thetoxicity of cyanide, great care must be exercised in itshandling. Acidification of cyanide solutions produces toxichydrocyanic acid
24、 (HCN). All manipulations must be done inthe hood so that any HCN gas that might escape is safelyvented.9.2 Residual sample remains could be toxic; these should bedisposed of properly.10. Sampling10.1 Collect the sample in accordance with SpecificationD 1192 and Practices D 3370.10.2 Thiocyanate is
25、stable in both the acid and alkaline pHrange.10.3 If the sample is to be preserved for cyanide, remove thesulfide before stabilization at a high pH (see section 10.3.2 ofTest Methods D 2036). Cyanide can be converted into thiocy-anate in the presence of sulfide at a high pH.10.4 Thiocyanate is biode
26、gradable. Samples that may con-tain bacteria should be preserved at pH2bytheaddition ofmineral acid and refrigerated.11. Preparation and Use of Resin Column11.1 Measure out sufficient resin to fill the column orcolumns into a beaker and add five times the resin volume ofacetone. Stir for 1 h with ge
27、ntle agitation.11.2 Pour off the fines and the acetone from the settled resinand add five times the resin volume of hexane. Stir for1h.11.3 Pour off any fines that may be present and the hexanefrom the settled resin and add five times the resin volume ofmethanol. Stir for 15 min.11.4 Pour off the me
28、thanol from the settled resin and addthree times the resin volume of NaOH solution (4 g/L). Stir for15 min.11.5 Pour off the NaOH solution from the settled resin andadd three times the resin volume of 0.1 M HNO3. Stir for 15min.11.6 Pour off the HNO3solution from the settled resin andadd three times
29、 the resin volume of reagent water. Stir for 15min. Decant the water from the settled resin and use thispurified resin to fill the column.11.7 Attach the tip of the column to a source of reagentwater, and displace the air from the column with water to thebottom of the reservoir (tip of the funnel if
30、 a buret is used).7Newman, A. A. (ed.), Chemistry and Biochemistry of Thiocyanic Acid and ItsDerivatives, Academic Press, New York, NY, 1975.8Shriner, R. L., and Fuson, R. C., Identification of Organic Compounds, JohnWiley cyanogen chloride; ferric ions; macroreticularresin (XAD-8); spectrophotomete
31、r; thiocyanateThis standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addre
32、ssed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at t
33、he address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (p
34、hone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 1 Bias for Thiocyanate Test MethodAmountAdded,mg/LAmountFound,mg/LnSTSOBias % BiasStatisticallySignificant(95 % Con-fidence Level)Reagent Water1.42 1.411 30 0.181 0.080 0.009 0.6 no0.71 0.683 27 0.091 0.027 0.027 4 no0.35 0.329 30 0.084 0.029 0.021 6 no0.07 0.068 30 0.052 0.018 0.002 3 noSelected Water Matrices1.42 1.408 26 0.151 0.046 0.012 0.8 no0.71 0.668 29 0.096 0.051 0.042 6 yes0.35 0.320 29 0.085 0.025 0.030 9 no0.07 0.050 29 0.079 0.014 0.020 29 noD 4193 024
