一个新的预处理和改进的方法确定选定的雌激素在高固体污水样品用液体矩阵相色谱质谱联用技术
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Anewpretreatmentandimprovedmethodfordeterminationofselectedestrogensinhighmatrixsolidsewagesamplesbyliquidchromatographymassspectrometry
QingcaiChen,JianghongShi⁎,WeiWu,XiaoweiLiu,HuiZhangStateKeyLaboratoryofWaterEnvironmentSimulation,SchoolofEnvironment,BeijingNormalUniversity,Beijing100875,PRChina
abstractarticleinfoArticlehistory:Received22March2012Receivedinrevisedform16April2012Accepted16April2012Availableonline20April2012
Keywords:EstrogenMatrixeffectLC–MS/MSOptimizationofpretreatmentmethodAqueousalkaliextractionSolidsamples
Thisarticledescribesapretreatmentprocedureforsamplesthatpossesshighmatrixinterferencestobetteranalyzefourestrogensincludingestrone(E1),17β-estradiol(E2),estriol(E3)and17α-ethinylestradiol(EE2)andxenoestrogensbisphenolA(BPA)insolidsamples,includingtheactivatedsludgeandsedimentsamplesinvestigatedhere.Duringthepretreatmentprocedure,thetargetcompoundswereextractedfromthesamplesusingacceleratedsolventextraction(ASE),andtheextractedsampleswerethenpurifiedusingfourstepsforclean-up:liquid–liquidextraction(LLE),Florisilclean-up,aqueousalkaliextraction(AAE)andhydrophilic–lipophilicbalance(HLB)enrichment.Theabsoluterecoveriesoftheactivatedsludgeandsedimentwere88–97%and75–100%,respectively,andthelimitsofdetectionwerebothbelow0.1ngg−1.Aftertheactivatedsludgeandsedimentsampleswerepurifiedusingthefourclean-upsteps,theirmatrixinterferenceeffectsdecreasedto0.5–32%and−3.2–0.8%,respectively,andtheirabsorbancevalueswerealsoclearlyreduced.However,theactivatedsludgeandsedimentsamplesthatwereextractedbyASEbutwerenotpurifiedthroughtheabove-mentionedfourstepsresultedinmatrixinterferenceeffectsonthefourestrogensandBPAthatreached81–233%and47–95%,respectively,inwhichE3andBPAwerecompletelysuppressedintheactivatedsludgesamples.©2012ElsevierB.V.Allrightsreserved.
1.IntroductionRecently,bothnaturalandsyntheticestrogens,e.g.,E1,E2,E3,EE2andxenoestrogens,i.e.,BPAand4-tert-octylphenol(OP),nonylphenol(NP),havebeenshowntoexhibitendocrine-disruptingeffectsintheenvironmentandhavecausedwideconcerns[1,2].Increasingnumbersofreportsindicatedthatestrogensmightcausepotentialadverseeffectsonthereproductivehealthofhumans[3–5].Therearegrowingnum-bersofstudiesabouttheoccurrenceanddistributionofestrogensinriv-ers,lakesandotheraquaticenvironmentsaroundtheworld.TheresultsofthesestudieshaveshownthatconcentrationsofestrogenswerelowtongL−1levelsinaquaticenvironments[6–8].Duetothelowconcen-
trationsofestrogensindifferentenvironmentalmatrices,therehavebeenmanyrequestsforthepretreatmentofenvironmentalsamplesandforinstrumentalanalysismethods.Accordingly,establishinginex-pensiveanalyticalanddetectionmethodsthatresultingoodrecoverieshasbecomeatopicofconcernincurrentstudiesandabottleneckforfurtherinvestigationsregardingtheoccurrenceandfateofestrogensintheenvironment.Thedevelopmentofanalyticalinstrumentationsuchasgaschroma-tography–massspectrometry(GC–MS),gaschromatography–tandemmassspectrometry(GC–MS/MS)andliquidchromatography–tandem
massspectrometry(LC–MS/MS)hassuppliedthetechnicalsupportthathasbeenneededfortheanalysisoftrace-levelandultratrace-levelorganiccompounds.Inrecentyears,chromatography–massspec-trometryhasbeenusedtomeasureestrogenicsamplesinvariousenvi-ronmentalmedia[9,10].However,manysamplesarenotsufficientlycleanedupand/orenrichedpriortoinstrumentalanalysis,thematrixinterferencesinsamplesbecomeanecessaryproblemtosolve,especial-lyforLC–MS/MSanalysis.Duringsampleanalysis,matrixeffectscansuppressormagnifythesignalintensitiesofestrogens,theseeffectsde-creasetherecoveriesofanalyticalmethodsandworsenthereproduc-ibilityoftheresults[2,11,12].Solidphaseextraction(SPE),aquickandsimpletechniquethatiscommonlyusedforsamplepretreatment,hasbeenwidelyusedfortheenrichmentandclean-upofestrogenicsamples[13,14].WiththedevelopmentoftheSPEtechniques,theclean-upprocedureofonesampleoftensequentiallyusedseveralSPEcolumnswithdifferentsorbentsthatpossessdifferentselectivities,inordertoeventuallyseparatethetargetcompounds[15,16].However,theclean-upeffectivenessandrecoveryoftargetcompoundsusingSPEcolumnscannotsimultaneouslybeoptimized.Sincethesecar-tridgestypicallyseparatethetargetcompoundsfromthematrixusingtheirdifferentpolarities,theimpuritieswhosepolaritiesaresimilartothetargetcompoundscannotbesufficientlyeliminatedandtheseim-puritiesarethesourceofsignalinterferenceinLC–MS/MS.Bythinkingabouttheirmolecularstructurecharacteristics,theauthorsfoundthatallestrogenswereweakacidsthatcontainedphenolichydroxyls.Previ-ousreportindicatedthatalkalineNaOHsolutioncanextractE2from