EPA 4025 SCREENING FOR POLYCHLORINATED DIBENZODIOXINS AND POLYCHLORINATED

《EPA 4025 SCREENING FOR POLYCHLORINATED DIBENZODIOXINS AND POLYCHLORINATED》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、METHOD4025SCREENINGFORPOLYCHLORINATEDDIBENZODIOXINSANDPOLYCHLORINATEDDIBENZOFURANS(PCDD/Fs)BYIMMUNOASSAY1.0SCOPEANDAPPLICATION1.1Method4025isaprocedurefortheanalysisofPolyChlorinatedDibenzoDioxinsandPolyChlorinatedDibenzoFurans(PCDD/Fs)insoilat500ppt(

2、pg/g).Method4025usesanEnzymeImmunoassay(EIA)commerciallyavailabletestkitcontainingapolyclonalantibodyspecificforPCDD/Fs.TheEIAkitisdesignedforthescreeningofsamplesaccordingtotheirtoxicequivalentconcentration(TEQ)byrespondingtothetoxicPCDD/Fcongenersin

3、approximatecorrelationwiththeirtoxicequivalencyfactors(TEFs).ThetestiscapableofmultiplecongenerrecognitionandpreferentiallytargetscongenerswithhighTEFvalues;i.e.,thosewiththehighesttoxicityrelativeto2,3,7,8-TetraChloroDibenzo-p-Dioxin(2,3,7,8-TCDD).Th

4、efinalmeasuredEIAresponseisthesumoftheindividualcongenerresponses.ThisresponsecorrelateswithTEQbecausetheimmunoassaycross-reactionprofileforPCDD/FscorrelateswithTEFvalues.SeeTable2foradetailedcross-reactionprofile.1.2ThetestingproductevaluatedbyEPAfor

5、thismethodemploysacompetitiveenzymeimmunoassay.Itisimportanttonotethatthismethoddiffersfromother4000seriesimmunoassaymethodsduetothespecificchemistryoftheanalyte.Thechemistryofdioxinanalysisismoredifficult,asshownbythecostandturnaroundtimedifferencesb

6、etweendioxin/furananalysis(e.g.Method8280/8290)andPCBanalysis(e.g.Method8082).Dioxinsare3to4ordersofmagnitudelesswatersolublethanmostother4000seriestargetanalytes.Additionally,sensitivitytargetscanbeordersofmagnitudelowerthanforPCBsandotheranalytes,so

7、thematrixconcentrationfactorscanbeextremeandextractsgenerallyrequirepartialcleanup.1.3ThePCDD/Fcongenercompositionofsamplescanbehighlyvariable.BecausePCDD/Fsareformedunintentionallybyavarietyofchemicalandcombustionprocesses,samplesusuallycontainamixtu

8、reofmanydifferentcongeners.Samplesfromdifferentsourcesoftenhaveverydifferentmixturesofcongenerswhichareconsistentwithinthesource.Inmostsamples,themajorityofthePCDD/FmasspresentdoesnotcontributesignificantlytothetotalsampleTEQ.Also,inmostsample