EPA METHOD 7471B Mercury in Solid or Semisolid Waste

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1、METHOD7471BMERCURYINSOLIDORSEMISOLIDWASTE(MANUALCOLD-VAPORTECHNIQUE)1.0SCOPEANDAPPLICATION1.1Method7471isapprovedformeasuringtotalmercury(organicandinorganic)insoils,sediments,bottomdeposits,andsludge-typematerials.Allsamplesmustbesubjectedtoanappropriatedissolutionsteppriortoanalysis.Ifthisdissolut

2、ionprocedureisnotsufficienttodissolveaspecificmatrixtypeorsample,thenthismethodisnotapplicableforthatmatrix.2.0SUMMARYOFMETHOD2.1Priortoanalysis,thesolidorsemi-solidsamplesmustbepreparedaccordingtotheproceduresdiscussedinthismethod.2.2Thismethodisacold-vaporatomicabsorptionmethodandisbasedontheabsor

3、ptionofradiationatthe253.7-nmwavelengthbymercuryvapor.Themercuryisreducedtotheelementalstateandaeratedfromsolutioninaclosedsystem.Themercuryvaporpassesthroughacellpositionedinthelightpathofanatomicabsorptionspectrophotometer.Absorbance(peakheight)ismeasuredasafunctionofmercuryconcentration.2.3Thetyp

4、icalinstrumentdetectionlimit(IDL)forthismethodis0.0002mg/L.3.0DEFINITIONSRefertoChapterOneandChapterThreeforalistingofapplicabledefinitions.4.0INTERFERENCES4.1Potassiumpermanganateisaddedtoeliminatepossibleinterferencefromsulfide.Concentrationsashighas20mg/Kgofsulfide,assodiumsulfide,donotinterferew

5、iththerecoveryofaddedinorganicmercuryinreagentwater.4.2Copperhasalsobeenreportedtointerfere;however,copperconcentrationsashighas10mg/Kghadnoeffectonrecoveryofmercuryfromspikedsamples.4.3Sampleshighinchloridesrequireadditionalpermanganate(asmuchas25mL)because,duringtheoxidationstep,chloridesareconver

6、tedtofreechlorine,whichalsoabsorbsradiationof254nm.Caremustthereforebetakentoensurethatfreechlorineisabsentbeforethemercuryisreducedandsweptintothecell.Thismaybeaccomplishedbyusinganexcessofhydroxylaminesulfatereagent(25mL).Inaddition,thedeadairspaceintheBODbottlemustbepurgedbeforeaddingstannoussulf

7、ate.4.4Certainvolatileorganicmaterialsthatabsorbatthiswavelengthmayalsocauseinterference.Apreliminaryrunwithoutreagentsshoulddetermineifthistypeofinterferenceispresent.CD-ROM7471B-1Revision2January199