ASTM_D_4282_-_15.pdf

Designation:D428215Standard Test Method forDetermination of Free Cyanide in Water and Wastewater byMicrodiffusion1This standard is issued under the fixed designation D4282;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 indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of freecyanides in waters and wastewaters.Free cyanide is heredefined as the cyanide which diffuses as cyanide(HCN),atroom temperature,from a solution at pH 6.21.2 This test method does not include complexes that resistdissociation,such as hexacyanoferrates and gold cyanide,nordoes it include thiocyanate and cyanohydrin.1.3 This test method may be applied to water and wastewa-ter samples containing free cyanide from 10 to 150 g/L.Greater concentrations may be determined by appropriatedilution.1.4 This test method has been fully validated by collabora-tive testing as specified by Practice D2777.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 This standard does not purport to address 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 specific hazardstatements,see 8.6,8.9,Section 9,and 12.2.1.2.Referenced Documents2.1 ASTM Standards:3D1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits(Withdrawn 2003)4D1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3856 Guide for Management Systems in LaboratoriesEngaged in Analysis of WaterD4210 Practice for Intralaboratory Quality Control Proce-dures and a Discussion on Reporting Low-Level Data(Withdrawn 2002)4D5788 Guide for Spiking Organics into Aqueous SamplesD5789 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Organic Constituents(Withdrawn 2002)4D5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible Spectrophotometers3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard,refer toTerminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 free cyanidethose simple cyanides or loosely heldcyanide complexes that diffuse at pH 6,at room temperature.4.Summary of Test Method4.1 The reactions are carried out in a microdiffusion cell.4.2 The sample is treated with cadmium ion to precipitatethe hexacyanoferrates.4.3 The sample is buffered at pH 6 and allowed to stand for4 h.4.4 The HCN diffuses into sodium hydroxide solution.4.5 An aliquot of the sodium hydroxide solution is treatedwith chloramine-T,and the cyanogen chloride formed is1This 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 15,2015.Published July 2015.Originallyapproved in 1983.Last previous edition approved in 2015 as D4282 02(2015).DOI:10.1520/D4282-R15.2The paper by J.M.Kruse and L.E.Thibault“Determination of Free Cyanidein Ferro-and Ferricyanides,”Analytical Chemistry,45(13):22602261;1973 Nov.,recommends a diffusion at pH 7.TheANSI modification(ANSI PH 4.41-1978)usespH 6.Using the conditions of the ANSI method,diffusion is completed within 4hours at pH 6.Longer diffusion time was required at pH 7 on the samples analyzed.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 reacted with barbituric acid in pyridine.The absorbance of thecolor formed is measured using a spectrophotometer at awavelength of 580 nm.5.Significance and Use5.1 This test method is useful in distinguishing between thepotentially available free cyanide(total cyanide)and the freecyanide actually present.5.2 This test method provides a convenient technique formaking on-site free cyanide determinations.6.Interferences6.1 Decomposition of Hexacyanoferrates During Diffusion:6.1.1 This decomposition is virtually eliminated by allow-ing the sample to diffuse in the dark,and by precipitating thehexacyanoferrates with cadmium ion.6.2 Instability of Free Cy