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1、METHOD7062ANTIMONYANDARSENIC(ATOMICABSORPTION,BOROHYDRIDEREDUCTION)1.0SCOPEANDAPPLICATION1.1Method7062isanatomicabsorptionprocedurefordetermining1µg/Lto400µg/Lconcentrationsofantimonyandarsenicinwastes,mobilityprocedureextracts,soils,andgroundwater.Method7062isapprovedforsamplematrice
2、sthatcontainuptoatotalof4000mg/Lconcentrationsofcobalt,copper,iron,mercury,ornickel.Asolidsamplecancontainupto40%byweightoftheinterferentsbeforeexceeding4000mg/Linadigestedsample.Allsamplesincludingaqueousmatricesmustbesubjectedtoanappropriatedissolutionsteppriortoanalysis.Spikedsampl
3、esandrelevantstandardreferencematerialsareusedtodeterminetheapplicabilityofthemethodtoagivenwaste.2.0SUMMARYOFMETHOD2.1SamplesarepreparedaccordingtothenitricaciddigestionproceduredescribedinMethod3010foraqueousandextractsamplesandthenitric/peroxide/hydrochloricaciddigestionprocedurede
4、scribedinMethod3050(furnaceAAoption)forsediments,soils,andsludges.Excessperoxideisremovedbyevaporatingsamplestoneardrynessattheendofthedigestionfollowedbydegassingthesamplesuponadditionofurea.L-cysteineisthenaddedasamaskingagent.Next,theantimonyandarsenicinthedigestarereducedtothetriv
5、alentformswithpotassiumiodide.Thetrivalentantimonyandarsenicarethenconvertedtovolatilehydridesusinghydrogenproducedfromthereactionoftheacidifiedsamplewithsodiumborohydrideinacontinuous-flowhydridegenerator.2.2Thevolatilehydridesaresweptinto,anddecomposein,aheatedquartzcelllocatedinthe
6、opticalpathofanatomicabsorptionspectrophotometer.Theresultingabsorptionofthelampradiationisproportionaltothearsenicorantimonyconcentration.2.3Thetypicaldetectionlimitforthismethodis1.0µg/L.3.0INTERFERENCES3.1Veryhigh(>4000mg/L)concentrationsofcobalt,copper,iron,mercury,andnickelcancau
7、seanalyticalinterferencesthroughprecipitationasreducedmetalsandassociatedblockageoftransferlinesandfittings.3.2Tracesofperoxidesleftfollowingthesamplework-upcanresultinanalyticalinterferences.Peroxidesmustberemovedbyevaporatingeachsampletoneardrynessfollowedbyreactionwithureaandallowi
8、ngsuf
