EPA METHOD 7473 Mercury in Solids and Solutions by Thermal

《EPA METHOD 7473 Mercury in Solids and Solutions by Thermal 》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、METHOD7473MERCURYINSOLIDSANDSOLUTIONSBYTHERMALDECOMPOSITION,AMALGAMATION,ANDATOMICABSORPTIONSPECTROPHOTOMETRY1.0SCOPEANDAPPLICATION1.1Method7473isdesignatedforthedeterminationofmercury(CASNo.7439-97-6)insolids,aqueoussamples,anddigestedsolutionsinboththelaboratoryandfieldenvironments.Integrationo

2、fthermaldecompositionsamplepreparationandatomicabsorptiondetectionreducesthetotalanalysistimeofmostsamplestolessthanfiveminutesineitherthelaboratoryorfieldsetting.Totalmercury(organicandinorganic)insoils,sediments,bottomdeposits,andsludge-typematerialsaswellasinaqueouswastesandgroundwaterscanbede

3、terminedwithoutsamplechemicalpretreatmentusingthismethod,exceptasnoted.Alternatively,thismethodcanbeusedforthedetectionoftotalmercuryfromtotaldecompositionsamplepreparationmethods,suchasMethod3052,orfordetectionofextractedorleachedmercurycompoundsorspeciesfrommethodssuchastheSW-8463000seriesmetho

4、ds(asdetailedinChapterThree).NOTE:Foruniquecircumstanceswhenmercurycouldbeboundinsilicatesorothermatricesthatmaynotthermallydecompose,validationofdirectanalysisofthesolidshouldbeconfirmedwithtotaldecompositionwithanEPAapprovedmethod(suchasMethod3052)andanalysiswiththismethod.2.0SUMMARYOFMETHOD2.1

5、Controlledheatinginanoxygenateddecompositionfurnaceisusedtoliberatemercuryfromsolidandaqueoussamplesintheinstrument.Thesampleisdriedandthenthermallyandchemicallydecomposedwithinthedecompositionfurnace.Thedecompositionproductsarecarriedbyflowingoxygentothecatalyticsectionofthefurnace.Hereoxidation

6、iscompletedandhalogensandnitrogen/sulfuroxidesaretrapped.Theremainingdecompositionproductsarethencarriedtoanamalgamatorthatselectivelytrapsmercury.Afterthesystemisflushedwithoxygentoremoveanyremaininggasesordecompositionproducts,theamalgamatorisrapidlyheated,releasingmercuryvapor.Flowingoxygencar

7、riesthemercuryvaporthroughabsorbancecellspositionedinthelightpathofasinglewavelengthatomicabsorptionspectrophotometer.Absorbance(peakheightorpeakarea)ismeasuredat253.7nmasafunctionofmercuryconcentration.2.2Thetypicalwo