ASTM_D_7284_-_13.pdf

Designation:D728413Standard Test Method forTotal Cyanide in Water by Micro Distillation followed byFlow Injection Analysis with Gas Diffusion Separation andAmperometric Detection1This standard is issued under the fixed designation D7284;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 is used to determine the concentrationof total cyanide in an aqueous wastewater or effluent.Themethod detects the cyanides that are free(HCN and CN-)andstrong-metal-cyanide complexes that dissociate and releasefree cyanide when refluxed under strongly acidic conditions.1.2 This method may not be applicable to process solutionsfrom precious metals mining operations.1.3 This procedure is applicable over a range of approxi-mately 2 to 500 g/L(parts per billion)total cyanide.Higherconcentrations can be measured with sample dilution or lowerinjection volume.1.4 The determinative step of this method utilizes flowinjection with amperometric detection based on Test MethodD6888.Prior to analysis,samples must be distilled with amicro-distillation apparatus described in this test method orwith a suitable cyanide distillation apparatus specified in TestMethods D2036.1.5 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.Specific hazardstatements are given in 8.6 and Section 9.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2036 Test Methods for Cyanides in WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3856 Guide for Management Systems in LaboratoriesEngaged in Analysis of WaterD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD6696 Guide for Understanding Cyanide SpeciesD6888 Test Method for Available Cyanide with LigandDisplacement and Flow InjectionAnalysis(FIA)UtilizingGas Diffusion Separation and Amperometric DetectionD7365 Practice for Sampling,Preservation and MitigatingInterferences in Water Samples for Analysis of CyanideE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminology D1129 and Guide D6696.3.2 Definitions of Terms Specific to This Standard:3.2.1 total cyanideTotal cyanide is an analytically definedterm that refers to the sum total of all of the inorganic chemicalforms of cyanide that dissociate and release free cyanide whenrefluxed under strongly acidic conditions.Total cyanide isdetermined analytically through strong acid distillation or UVradiation followed by analysis of liberated free cyanide onaqueous samples preserved with NaOH(pH12).In water,total cyanide includes the following dissolved species:freecyanide,weak acid dissociable metal cyanide complexes andstrong metal cyanide complexes.Also,some of the strongmetal cyanide complexes,such as those of gold,cobalt andplatinum,might not be fully recovered during the total cyanideanalytical procedure.Additionally,total cyanide may alsoinclude some organic forms of cyanide such as nitriles thatrelease free cyanide under the conditions of the analysis.1This 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 June 15,2013.Published July 2013.Originallyapproved in 2008.Last previous edition approved in 2008 as D7284 081.DOI:10.1520/D7284-13.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Summary of Test Method4.1 The samples are distilled with a strong acid in thepresence of magnesium chloride catalyst and captured insodium hydroxide absorber solution.4.2 The absorber solution is introduced into a flow injectionanalysis(FIA)system where it is acidified to form hydrogencyanide(HCN).The hydrogen cyanide gas diffuses through ahydrophobic gas diffusion membrane,from the acidic donorstream into an alkaline acceptor stream.4.3 The captured cyanide is sent to an amperometric flow-cell detector with a silver-wo