EPA METHOD 3020A Acid Digestion of Aqueous Samples

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1、METHOD3020AACIDDIGESTIONOFAQUEOUSSAMPLESANDEXTRACTSFORTOTALMETALSFORANALYSISBYGFAASPECTROSCOPY1.0SCOPEANDAPPLICATION1.1Thisdigestionprocedureisusedforthepreparationofaqueoussamples,mobility-procedureextracts,andwastesthatcontainsuspendedsolidsforanalysisbyfurnaceatomicabsorptionspectros

2、copy(GFAA)forthemetalslistedbelow.Theprocedureisusedtodeterminethetotalamountofthemetalinthesample.1.2SamplespreparedbyMethod3020maybeanalyzedbyGFAAforthefollowingmetals:BerylliumLeadCadmiumMolybdenumChromiumThalliumCobaltVanadiumNOTE:ForthedigestionandGFAAanalysisofarsenicandselenium,s

3、eeMethods7060and7740.ForthedigestionandGFAAanalysisofsilver,seeMethod7761.2.0SUMMARYOFMETHOD2.1AmixtureofnitricacidandthematerialtobeanalyzedisrefluxedinacoveredGriffinbeaker.Thisstepisrepeatedwithadditionalportionsofnitricaciduntilthedigestateislightincolororuntilitscolorhasstabilized.

4、Afterthedigestatehasbeenbroughttoalowvolume,itiscooledandbroughtupindilutenitricacidsuchthatthefinaldilutioncontains3%(v/v)nitricacid.Thispercentagewillvarydependingontheamountofacidusedtocompletethedigestion.Ifthesamplecontainssuspendedsolids,itmustbecentrifuged,filtered,orallowedtoset

5、tle.3.0INTERFERENCES3.1Interferencesarediscussedinthereferringanalyticalmethod.4.0APPARATUSANDMATERIALS4.1Griffinbeakers-150-mL,orequivalent.4.2Watchglasses-ribbedorequivalent.CD-ROM3020A-1Revision1July19924.3Qualitativefilterpaperorcentrifugationequipment.4.4Funnelorequivalent.4.5Gradu

6、atedCylinder-100mL.4.6Electrichotplateorequivalent-adjustableandcapableofomaintainingatemperatureof90-95C.5.0REAGENTS5.1Reagentgradechemicalsshallbeusedinalltests.Unlessotherwiseindicated,itisintendedthatallreagentsshallconformtothespecificationsoftheCommitteeonAnalyticalReagentsoftheAm

7、ericanChemicalSociety,wheresuchspecificationsareavailable.Othergradesmaybeused,provideditisfirstascertainedthatthereagentisofsufficientlyhighpuritytopermititsusewithoutlesseningtheaccuracyofthedetermination.5.2ReagentWater.Reagentwaterwillbeinterferencefree.Allreferencestowater