資源描述：
《EPA METHOD 7470A Mercury in Liquid Waste (Manual Cold-Vapor Technique)》由會(huì)員上傳分享，免費(fèi)在線閱讀，更多相關(guān)內(nèi)容在行業(yè)資料-天天文庫(kù)。
1、METHOD7470AMERCURYINLIQUIDWASTE(MANUALCOLD-VAPORTECHNIQUE)1.0SCOPEANDAPPLICATION1.1Method7470isacold-vaporatomicabsorptionprocedureapprovedfordeterminingtheconcentrationofmercuryinmobility-procedureextracts,aqueouswastes,andgroundwaters.(Method7470canalsobeusedforanalyzin
2、gcertainsolidandsludge-typewastes;however,Method7471isusuallythemethodofchoiceforthesewastetypes.)Allsamplesmustbesubjectedtoanappropriatedissolutionsteppriortoanalysis.2.0SUMMARYOFMETHOD2.1Priortoanalysis,theliquidsamplesmustbepreparedaccordingtotheprocedurediscussedinth
3、ismethod.2.2Method7470,acold-vaporatomicabsorptiontechnique,isbasedontheabsorptionofradiationat253.7-nmbymercuryvapor.Themercuryisreducedtotheelementalstateandaeratedfromsolutioninaclosedsystem.Themercuryvaporpassesthroughacellpositionedinthelightpathofanatomicabsorptions
4、pectrophotometer.Absorbance(peakheight)ismeasuredasafunctionofmercuryconcentration.2.3Thetypicaldetectionlimitforthismethodis0.0002mg/L.3.0INTERFERENCES3.1Potassiumpermanganateisaddedtoeliminatepossibleinterferencefromsulfide.Concentrationsashighas20mg/Lofsulfideassodiums
5、ulfidedonotinterferewiththerecoveryofaddedinorganicmercuryfromreagentwater.3.2Copperhasalsobeenreportedtointerfere;however,copperconcen-trationsashighas10mg/Lhadnoeffectonrecoveryofmercuryfromspikedsamples.3.3Seawaters,brines,andindustrialeffluentshighinchloridesrequiread
6、ditionalpermanganate(asmuchas25mL)because,duringtheoxidationstep,chloridesareconvertedtofreechlorine,whichalsoabsorbsradiationof253.7nm.Caremustthereforebetakentoensurethatfreechlorineisabsentbeforethemercuryisreducedandsweptintothecell.Thismaybeaccomplishedbyusinganexces
7、sofhydroxylaminesulfatereagent(25mL).Inaddition,thedeadairspaceintheBODbottlemustbepurgedbeforeaddingstannoussulfate.Bothinorganicandorganicmercuryspikeshavebeenquantitativelyrecoveredfromseawaterbyusingthistechnique.3.4Certainvolatileorganicmaterialsthatabsorbatthiswavel
8、engthmayalsocauseinterference.Apreliminaryrunwithoutreagentsshoulddetermineifthistypeofinterfere
