Designation:D3868−15StandardTestMethodforFluorideIonsinBrackishWater,Seawater,andBrines1ThisstandardisissuedunderthefixeddesignationD3868;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethod2coversthedeterminationofsolublefluorideionsinbrackishwater,seawaterandbrinesbyuseofafluorideselectiveelectrode.1.2Samplescontainingfrom1.0to25mg/Lcanbeana-lyzedbythistestmethod.1.3ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:3D1129TerminologyRelatingtoWaterD1193SpecificationforReagentWaterD2777PracticeforDeterminationofPrecisionandBiasofApplicableTestMethodsofCommitteeD19onWaterD3370PracticesforSamplingWaterfromClosedConduitsD5847PracticeforWritingQualityControlSpecificationsforStandardTestMethodsforWaterAnalysis3.Terminology3.1Definitions—Fordefinitionsoftermsusedinthistestmethod,refertoTerminologyD1129.4.SummaryofTestMethod4.1Afluorideselectiveelectrode,referenceelectrode,andmillivoltmeterareusedtodeterminefluorideinbrinesamplesbyastandardadditionmethod.4.2Thefluorideselectiveelectrodeconsistsofalanthanumfluoridecrystalthatdevelopsanelectrodepotentialcorre-spondingtotheleveloffluorideioninsolution.5.SignificanceandUse5.1Identificationofabrackishwater,seawater,orbrineisdeterminedbycomparisonoftheconcentrationsoftheirdissolvedconstituents.Theresultsareusedtoevaluatetheoriginofthewater,determineifitisapossiblepollutant,orifitisrelatedtoapotentialsourceofavaluablemineral.Forexample,ingeochemicalstudiessomecorrelationdata...
