Designation:D5257−17StandardTestMethodforDissolvedHexavalentChromiuminWaterbyIonChromatography1ThisstandardisissuedunderthefixeddesignationD5257;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodcoversproceduresforthedetermina-tionofdissolvedhexavalentchromiuminwastewater,surfacewater,anddrinkingwater.1.2Theprecisionandbiasofthistestmethodhasbeentestedinreagentwaterandindustrialwastewaterandhasbeenfoundsuitableovertherangeofapproximately1to1000µg/L.Higherlevelscanbedeterminedbyappropriatedilution.1.3Samplescontainingveryhighlevelsofanionicspecies(thatis,chloride,sulfate,etc.)maycausecolumnoverload.Samplescontaininghighlevelsofreducingspecies(thatis,sulfides,sulfites,etc.)maycausereductionofCr(VI)toCr(III).ThiscanbeminimizedbybufferingthesampletoapHof9to9.5,filteringit,storingitat<6°C.Aholdingtimeof28daysmaybeusediftheusercandemonstratethatsuchholdingtimedoesnotaffectsampleintegrityinaccordancewithU.S.EPA40CFR136,PartII.1.4ThevaluesstatedinSIunitsaretoberegardedasstandard.Thevaluesgiveninparenthesesaremathematicalconversionstoinch-poundunitsthatareprovidedforinforma-tiononlyandarenotconsideredstandard.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.6Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.2.ReferencedDocuments2.1ASTMStandards:2D1066PracticeforSamplingSteamD1129TerminologyRelatingtoWaterD11...
