EPA METHOD 3031 Acid Digestion of Oils for Metals

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1、METHOD3031ACIDDIGESTIONOFOILSFORMETALSANALYSISBYATOMICABSORPTIONORICPSPECTROMETRY1.0SCOPEANDAPPLICATION1.1Thismethodisanaciddigestionprocedureforanalysisofoils,oilsludges,tars,waxes,paints,paintsludgesandotherviscouspetroleumproductsforthesixteentoxicelementslistedbel

2、ow:AntimonyArsenicBariumBerylliumCadmiumChromiumCobaltCopperLeadMolybdenumNickelSeleniumSilverThalliumVanadiumZincOtherelementsandmatricesmaybeanalyzedbythismethodifperformanceisdemonstratedfortheanalytesofinterest,inthematrixofinterest,attheconcentrationlevelsofinter

3、est(seeSection8.0).Theresultingdigestatecanbeanalyzedbyeitherflameatomicabsorptionspectrometry(FLAA),graphitefurnaceatomicabsorptionspectrometry(GFAA),orinductivelycoupledplasmaatomicemissionspectrometry(ICP-AES).1.2Thelargeconcentrationofmanganesepresentinthedigestat

4、eofMethod3031caninterferewiththedeterminationoflowconcentrationsofarsenicwhichisimportantfortherecycledoilregulations.Asanoptionalstep,manganesemayberemovedfromthedigestatebyformingamanganesephosphateprecipitate.Theremainingliquidcanbeanalyzedbyeitherflameatomicabsorp

5、tionspectrometry(FLAA)orinductivelycoupledplasma(ICP-AES).Chloridescanberemovedbytheuseofnitricacidforanalysisbygraphitefurnaceatomicabsorptionspectrometry(GFAA)forarsenic.Theseclean-upproceduresmaybeapplicabletootherelementsascanbedemonstratedbyappropriateprocedures(

6、Sec.7.11).2.0SUMMARYOFMETHOD2.1Arepresentative0.5gsampleismixedwith0.5goffinelygroundpotassiumpermanganateandthen1.0mLofconcentratedsulfuricacidisaddedwhilestirring.Astrongexothermicreactionoccurs.Thesampleisthentreatedwith2mLconcentratednitricacid.10mLofconcentratedH

7、Clisaddedandthesampleisheateduntilthereactioniscompleteandisthenfiltered.ThefilteriswashedwithhotconcentratedHCl.Thefilterpaperistransferredtoadigestionflask,treatedwith5mLofconcentratedhydrochloricacid.ThesampleisbroughttovolumeandanalyzedbyICP-AESorFLAA.WARNING:THIS

8、PROCEDURESHOULDNOTBEATTEMPTEDBYINEXPERIENCEDPERSONNEL.MANYOFTHEREACTIONSARESTRONGLYEXOTHERMICANDCANRESULTINSPLATTERINGORINTH