化学计量学方法来识别选择性离子重叠气相色谱

Achemometricmethodtoidentifyselectiveionforresolutionofoverlappinggaschromatography-massspectrometrysignal,(SCIENCECHINACHEMISTRY)(May2013Vol.56No.5:656663),姓名：李琴学号：212103019,Abstract,Achemometricmethodtodetermineselectiveionbyusingnon-negativeimmunealgorithm(NNIA)wasproposed.Inthemethod,themutualprojectionsofthechromatographicprofilesatdifferentm/zchannelarecalculatedusingNNIA.SupposeaGC-MSdatawithmretentiontimepointsandnmasschannels,theprojectionsoftheGC-MSdataontoachromatographicprofileatamasschannelwillformamassspectrumof1nvector.Ifthechromatographicprofileataselectivemasschannelisused,theextractedmassspectrumwillbeacorrectone.Therefore,bycomparingtheextractedmassspectrumwithareferencespectrum,theselectiveioncanbeidentified,andthecorrespondingchromatographicprofilecanbeobtainedatthesametime.GC-MSdataof40-pesticidemixturewasinvestigatedbythemethod.Theresultsshowthatboththemassspectralandthechromatographicinformationoftheinterestedcomponentscanbeextractedfromtheoverlappingsignals,exceptforthespecialcasesofisomericcomponentswithverysimilarmassspectra.,目录,1,2,3,4,Introduction,Calculation,Experimental,Resultsanddiscussion,5,Conclusions,1.Introduction,Inthiswork,NNIAwasadoptedforthedeterminationofselectiveioninaGC-MSdatamatrix.Intheapproach,themutualprojectionofthechromatographicprofilesinanmnGC-MSdatamatrixiscalculatedbyusingNNIA,thus,nextractedmassspectracanbeobtained.Amongthose,thespectrumobtainedbythechromatographicprofileoftheselectiveionwillbethecorrectone.Therefore,ifareferencemassspectrumisprovidedforanalyzingcomponent,theselectiveioncanbeidentifiedbycomparingtheextractedmassspectraandthereferenceone.Withtheselectiveionandthecorrespondingchromatographicprofile,theinformationofthecomponentcanbeextractedfromthedatamatrix.,2.Calculation,(1)Determinationofthereferencemassspectrum,(2)Calculationofthemutualprojections,(3)Identificationoftheselectiveion,(4)Subtractionofthecomponentfromthedatamatrix,(5)Repetition,(6)Correctionandrefinement,Figure1Schemefigureoftheproposedmethod.,3.Experimental,(1)Datasimulation,Afive-componentmixturewassimulatedfortestingtheperformanceofthemethod.TheGCprofilesofthefiveanalytesweresimulatedbythecommonlyusedexponentiallymodifiedGaussian(EMG)equation,andaconstantbackgroundwithrandomnoiseisaddedasthe6thcomponent.Allthemassspectraofthefivecomponentshave105m/zchannels,eachofwhichhasatleastoneselectiveionexceptforthe2ndone,andamassspectrumissimulatedasabackground.Therefore,thesimulatedsignalofGC-MSisa100105matrixthatisobtainedbymultiplyingthesixmassspectraandthesixchromatographicprofiles.,(2)Experimentdata,.,GC-MSdataof40-pesticidemixtureswasusedfortestingtheperformanceoftheproposedmethod.The40-pesticidemixturewasobtainedbymixingthestandardsinasolutionwithaconcentrationof10mgL-1,asreportedinRef.ThesamplewasanalyzedbyThermoGC-MSsystemconsistingofaTracegaschromatographwithacapillarycolumnofweakpolar,CP-Sil8CB(USA,Varian,30mlong,0.32mmi.d.,and0.25mfilmthickness)andaPolarisQmassspectrometry(USA,ThermoFisherScientific).Theelectronimpactionizationsource(EI)wasemployedandtunedat70eV.Themassrangefrom50to650muwasscanned.Thecarriergaswashelium(BOC,99.999%)withaflowrateof1.0mLmin-1.Furthermore,forspeedinguptheanalysisregardlessoftheresolution,averyfasttemperatureprogramwasused.Therefore,allthecomponentsinthemixtureareelutedwithin12min,asshowninFigure2.Inthiswork,theoverlappingpeakclustersinthethreeregions(4.744.86min,5.305.48minand5.675.84min)indicatedbytheredboxesareselectedasexamplestoinvestigatetheperformanceofthemethod.,Figure2TICofthepesticidemixture.Threeregionsenclosedbyredboxesareselectedasexamplestovalidatetheperformanceofthemethod.,4.Resultsanddiscussion,(1)Resolutionofthesimulateddata,(a1a5):Simulated.(b1)(b5):Resolvedmassspectrabeforethecorrectionandrefinementstep.(c1)(c5):Resolvedmassspectraaftercorrectionandrefinement.,.,ResolutionofthesimulatedGC-MSdata.(a)Resolvedchromatogramsbeforethecorrectionandrefinementstep,(b)correlationcoefficientsobtainedforthefirstcomponent,(c)correlationcoefficientsobtainedforthesecondcomponent,and(d)resolvedchromatogramsaftercorrectionandrefinement.,(2)ResolutionoftheexperimentalGC-MSsignals,ResolutionoftheexperimentalGC-MSdata.(a)Resolvedchromatogramsbeforethecorrectionandrefinementstep,(b)correlationcoefficientsobtainedforthefirstcomponent,(c)(f)resolvedmassspectraofthecomponentsbeforethecorrectionandrefinementstep.,Resolvedchromatograms(a)andmassspectra(b)(e)ofthecomponentsfromthefirstregionoftheexperimentalGC-MSdata.,.,Resolvedchromatograms(a)andmassspectra(b)(e)ofthecomponentsfromthesecondregionoftheexperimentalGC-MSdata.,.,Resolvedchromatograms(a)andmassspectra(b)(d)ofthecomponentsfromthethirdregionoftheexperimentalGC-MSdata.,5.Conclusions,AchemometricmethodtodetermineselectiveionbyusingNNIAwasproposed.Withtheproposedmethod,theselectiveionsofthecomponentsinoverlappingpeakscanbeidentified,andtheinformationoftheinterestedcomponentscanbeextracted.Resolutionofthesimulateddataindicatesthattheselectiveionscanbecorrectlyidentifiedalthoughtheidentificationofselectiveionmayfailwhenthereisnoselectiveion.However,duetothecorrectionandrefinementstep,themethodcanstillsuccesswhentheidentifiedselectiveioniscontaminatedbyalow