Designation:D5257−11StandardTestMethodforDissolvedHexavalentChromiuminWaterbyIonChromatography1ThisstandardisissuedunderthefixeddesignationD5257;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodcoversproceduresforthedetermina-tionofdissolvedhexavalentchromiuminwastewater,surfacewater,anddrinkingwater.1.2Theprecisionandbiasofthistestmethodhasbeentestedinreagentwaterandindustrialwastewaterandhasbeenfoundsuitableovertherangeofapproximately1to1000µg/L.SeeTable1fordetails.Higherlevelscanbedeterminedbyappropriatedilution.1.3Samplescontainingveryhighlevelsofanionicspecies(thatis,chloride,sulfate,etc.)maycausecolumnoverload.Samplescontaininghighlevelsofreducingspecies(thatis,sulfides,sulfites,etc.)maycausereductionofCr(VI)toCr(III).ThiscanbeminimizedbybufferingthesampletoapHof9to9.5,filteringit,storingitat<6°C.aAholdingtimeof28daysmaybeusediftheusercandemonstratethatsuchholdingtimedoesnotaffectsampleintegrityperUSEPA40CFR136PartII.1.4ThevaluesstatedineitherSIorinch-poundunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D1066PracticeforSamplingSteamD1129TerminologyRelatingtoWaterD1193SpecificationforReagentWaterD2777PracticeforDeterminationofPrecisionandBiasofApplicableTestMethodsofCommitteeD19onWaterD3370PracticesforSamplingWaterfromClosedConduitsD5810GuideforSpikingintoAqueousSamplesD5847PracticeforWritingQualityControlSpecificationsforStandardTestMethodsforWaterAnalysis2.2EPAStandard:EPAMethod218.6DeterminationofDissolvedHexavale...
