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1、1Solid-PhaseMicroextractioninPerspectiveJanuszPawliszynDepartmentofChemistry,UniversityofWaterloo,Waterloo,Ontario,Canada1.1SamplePreparationasPartoftheAnalyticalProcessTheanalyticalprocedureforcomplexsamplesconsistsofseveralstepsthattypi-callyincludesamp
2、ling,samplepreparation,separation,quantitation,statisticaleval-uationanddecisionmaking(Figure1.1).Eachstepiscriticalforobtainingcorrectandinformativeresults.Thesamplingstepincludesdecidingwheretogetsamplesthatproperlydefinetheobjectorprob-lembeingcharacte
3、risedandthenchoosingamethodtoobtainsamplesintherightamounts.Theobjectiveofthesamplepreparationstepistoisolatethecomponentsofinterestfromasamplematrix.Thisisbecausemostanalyticalinstrumentscan-nothandlethematrixdirectly.Samplepreparationinvolvesextractionp
4、roceduresandcanalsoincludeclean-upproceduresforverycomplexdirtysamples.Thisstepmustalsobringtheanalytestoasuitableconcentrationlevelfordetection;therefore,samplepreparationmethodstypicallyincludeenrichment.Duringtheseparationstepoftheanalyticalprocess,the
5、isolatedcomplexmixturecontainingtargetanalytesisdividedintoitsconstituents,typicallybymeansofchro-matographicorelectrophoretictechniques.Quantitationisthedeterminationofamountsoftheidentifiedcompounds.Theidentificationcanbebasedonareten-tiontimecombinedwi
6、thselectivedetection;morefrequently,however,instrumentsprovidingmorespecificinformation(namely,massspectrometers)areusedtoeliminatepossibleerrorsinquantificationduetointerferences.Statisticalevalua-tionoftheresultsprovidesanestimateofthetargetcompoundscon
7、centrationinthesamplebeinganalysed.Thedatawillthensupportappropriatedecisions,whichmightincludetakinganothersampleforfurtherinvestigation.Itisimportanttonote,asemphasisedinFigure1.1,thatanalyticalstepsfollowoneaftertheother,andasubsequentstepcannotbeginun
8、tiltheprecedingonehasbeencompleted.Therefore,thesloweststepdeterminestheoverallspeedoftheanalyticalprocess,andimprovingthespeedofasinglestepmaynotresultinathroughputincrease.Toincreasethethroughputofanalysis,allstep
