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1、METHOD9056DETERMINATIONOFINORGANICANIONSBYIONCHROMATOGRAPHY1.0SCOPEANDAPPLICATION1.1Thismethodaddressesthesequentialdeterminationoftheanionschloride,fluoride,bromide,nitrate,nitrite,phosphate,andsulfateinthecollectionsolutionsfromthebombcombustionofsolidwastesamples,aswellasallwatersam
2、ples.1.2Themethoddetectionlimit(MDL),theminimumconcentrationofasubstancethatcanbemeasuredandreportedwith99%confidencethatthevalueisabovezero,variesforanionsasafunctionofsamplesizeandtheconductivityscaleused.Generally,minimumdetectableconcentrationsareinthe-----3-2-rangeof0.05mg/LforFan
3、d0.1mg/LforBr,Cl,N03,N02,PO4,andSO4witha100-µLsampleloopanda10-µmhofull-scalesettingontheconductivitydetector.Similarvaluesmaybeachievedbyusingahigherscalesettingandanelectronicintegrator.Idealizeddetectionlimitsofanorderofmagnitudelowerhavebeendeterminedinreagentwaterbyusinga1-µmho/cm
4、full-scalesetting(Table1).Theupperlimitofthemethodisdependentontotalanionconcentrationandmaybedeterminedexperimentally.Theselimitsmaybeextendedbyappropriatedilution.2.0SUMMARYOFMETHOD2.1Asmallvolumeofcombustatecollectionsolutionorotherwatersample,typically2to3mL,isinjectedintoanionchro
5、matographtoflushandfillaconstantvolumesampleloop.Thesampleistheninjectedintoastreamofcarbonate-bicarbonateeluentofthesamestrengthasthecollectionsolutionorwatersample.2.2Thesampleispumpedthroughthreedifferentionexchangecolumnsandintoaconductivitydetector.Thefirsttwocolumns,aprecolumnorg
6、uardcolumnandaseparatorcolumn,arepackedwithlow-capacity,stronglybasicanionexchanger.Ionsareseparatedintodiscretebandsbasedontheiraffinityfortheexchangesitesoftheresin.Thelastcolumnisasuppressorcolumnthatreducesthebackgroundconductivityoftheeluenttoalowornegligiblelevelandconvertstheani
7、onsinthesampletotheircorrespondingacids.Theseparatedanionsintheiracidformaremeasuredusinganelectrical-conductivitycell.Anionsareidentifiedbasedontheirretentiontimescomparedtoknownstandards.Quantitationisaccomplishedbymeasuringthepeakheightorareaandcomparingittoacalibrationcurvegenera
