ASTM_D_4658_-_15.pdf

Designation:D465815Standard Test Method forSulfide Ion in Water1This standard is issued under the fixed designation D4658;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.Scope*1.1 This test method uses an ion-selective electrode todetermine sulfide ion in water.The test method is applicable inthe range from 0.04 to 4000 mg/L of sulfide.1.2 Precision data presented in this test method were ob-tained using reagent water only.It is the users responsibility toensure the validity of this test method for untested types ofwater.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 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.Sulfide samples,when acidified,can release highly toxic hydrogen sulfide gas.For a specific precautionary statement,see 7.5.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 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 ConduitsD4127 Terminology Used with Ion-Selective ElectrodesD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 For definitions of terms specific to this test method,refer to Terminology D4127.4.Summary of Test Method4.1 Sulfide ion is measured potentiometrically using asulfide ion-selective electrode in conjunction with a double-junction sleeve type reference electrode.Potentials are readusing a pH meter having an expanded millivolt scale capable ofbeing read to the nearest 0.1 mV,or a specific ion meter havinga direct concentration scale for sulfide ion.4.2 Samples are treated prior to analysis with sulfide anti-oxidant buffer(SAOB).This buffer fixes the solution pH at ahighly alkaline level and contains ascorbic acid to retard airoxidation of sulfide ion in solution.This ensures that the sulfidepresent occurs chiefly as S2ion rather than as complexed HS1or H2S that are present at lower pH values.5.Significance and Use5.1 Sulfide ion is found in ground waters and wastewater,causing odor and corrosion problems.If acidified,these waterscan release hydrogen sulfide,which is extremely toxic even atlow levels.This test method provides a means for interference-free measurement of free sulfide ion.NOTE1Sulfide forms complexes with hydrogen ions(HS1and H2S).In addition,sulfide ion forms soluble complexes with elemental sulfur(S22,S32,S42,etc.),tin,antimony,and arsenic ions.6.Apparatus6.1 pH Meter,with expanded millivolt scale,or a specificion meter having a direct concentration scale for sulfide ion.6.2 Sulfide Ion-Selective Electrode.6.3 Reference Electrode,double-junction sleeve type with1.0 M potassium nitrate solution,pH adjusted to 13.5 with 1.0M sodium hydroxide in the outer sleeve.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand are the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved March 15,2015.Published April 2015.Originallyapproved in 1987.Last previous edition approved in 2009 as D4658 09.DOI:10.1520/D4658-15.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Reagents7.1 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 onAnalytical Reagents of theAmerican Chemical Society.3Other grades may be used,provided it is first ascertained thatthe reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated,referenceto water shall be understood to mean reagent water conformingto Specification D1193,Type I.Other reagent water types maybe used provided it is first ascertained that the water is ofsufficiently high purity to permit its use without adverselyaffec