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1、6CalibrationGangfengOuyangSchoolofChemistryandChemicalEngineering,SunYat-senUniversity,Guangzhou,P.R.China6.1Introduction1Solid-phasemicroextraction(SPME)wasfirstintroducedin1990andwas2subsequentlyoptimisedandautomated.Itisasolvent-freesamplepreparationtechniquethatintegratessampling,isolationan
2、dconcentration.Also,itssimplicityofuse,relativelyshortsampleprocessingtimeandfibrereusabilityhavemadeSPME35anattractivechoiceformanyanalyticalapplications.Sincethattime,SPMEhas6101113beenwidelyappliedtothesamplingandanalysisofenvironmental,food,14,15161819242530aromatic,metallic,forensican
3、dpharmaceuticalsamples.InSPME,micro-quantitiesofsolidsorbentorliquidpolymerinanappropriateformatareexposedtothesampleforawell-definedperiodoftime.Quantificationisbasedontheamountofanalyteextractedundertheappropriateconditions.Unliketraditionalsamplepreparationmethods,suchasliquidliquidextractio
4、n(LLE),solid-phaseextraction(SPE)andSoxhlet,SPMEisanon-exhaustiveextractiontechniqueinwhichonlyasmallportionofthetargetanalyteisremovedfromthesamplematrix.Thisfeatureallowsthemonitoringofchemicalchanges,partitioningequilibriaandspeciationintheinvestigatedsystembecausesamplingcausesmini-31,32malp
5、erturbationtothesystem.Therefore,theuseofSPMEresultsinbettercharacterisationandmoreaccurateinformationabouttheinvestigatedsystemorpro-cesscomparedtoexhaustivetechniques.SPMEalsoprovidessignalmagnitudesthatareproportionaltothefreeconcentrationoftargetanalyte,definingthefractionoftheanalytethatisb
6、ioavailable.ThisuniquefeatureofSPMEallowsthemeasure-mentofbindingconstantsincomplexmatrices,providingadditionalinformation26,32,33abouttheinvestigatedsystem(seeChapter11).Non-exhaustiveextractionalsoindicatestheneedforcarefulcalibrationofSPMEforquantitativeanalysis.Anappropriatecalibrationmethod
7、forSPMEquantificationisrequired.Calibrationisaprocessrelatingthemeasuredanalyticalsignaltotheconcentra-tionofanalyteinthesamplematrix.SPMEcalibrationtechniquesuitabilitydependsontheapplication,thenumberofsamplestobeanalyseda
