现代仪器分析第八章质谱法教程文件.ppt

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1、现代仪器分析第八章质谱法通常的离子化方法电子轰击离子化EI化学电离离子化CI正化学电离离子化PCI负化学电离离子化NCI大气压力离子化API电喷雾离子化ESI大气压化学电离离子化APCIGC/MSLC/MS离子化方式分子量非极性极性EI/CIESIAPCI100,0001000离子化和碎片离子化硬无碎片有碎片APIEICI软质量分析器四极杆~80%的台式质谱仪(~3000/年)HP,PE,TMQ,Shimadzu离子阱~20%的台式质谱仪(~700/年)Varian,TMQ飞行时间(ToF)目前用户较少(50-60/年)Leco,Micromass,TMQ扇形磁场通常不

2、是台式仪器扇形磁场质量分析器+++离子通过变化的磁场和电场被传输四极质量分析器++++离子阱原理与四极杆的非常相似，离子被存储在RF和DC场中，扫描场逐出精确m/z的离子。飞行时间质量分析器++++所有离子同时启动小的离子移动速度快测量已知距离下的速度(飞行时间)ElectronImpactIonization(EI)e-e-e-e-e-SamplefromGCfilament++++FragmentionQPElectronImpactIonization(EI)Thermalelectrons(ca.70eV)hitmoleculesandionizethem.Am

3、plefragmentions=amplestructuralinformationFingerprintEIspectrumMethylstearateM.W.298PositiveChemicalIonization(PCI)fromgascylinderfilamente-e-e-e-e-QPCH4CH5+C2H5+SamplefromGCH+-CH4[M+1]-C2H4PositiveChemicalIonization(PCI)Reagentgasmoleculesareionizedfirst.Samplemoleculesareionizedmainly

4、by損rotontransfer?Quasimolecularionseasilyproducedusefulformolecularweightverification.+PCIspectrumMethylstearateM.W.298ComparisonofEIandPCIEImodePCImodeFragmentMolecularweightNegativeChemicalIonization(NCI)Negativeionformationbyelectroncaptureassociativeresonancecapturedissociativeresona

5、ncecaptureion-pairproductionNegativeionformationbyion-moleculereactionsprotontransferchargeexchangenucleophilicadditionnucleophilicdisplacementNegativeionformationbyelectroncapture(associativeresonancecapture)MX+e-(~0eV)MX-.X:positiveelectronaffinitypartCH4e-MXCH4+CH3+HCH4CH4CH4e-MX-质谱图的

6、样子?EI和CI的质谱图50100150200250300350400450500550m/z0100%51051151250100150200250300350400450500550m/z0100%241213510242EIOOOCF3CF3CH3NCI…扫描50到300amu流入质谱仪的化合物质谱图...60801001201401601802002202402602803000100%240241断裂机理1.σ断裂2.α断裂3.i断裂4.逆Diels-Alder反应5.Mclafferty重排ConfigurationofGCMSMassSpectromete

7、rGasChromatographInterfaceIonsourceboxIonSourceDesign-Increasedionizationefficacy-InterfaceThesampleseparatedbyGCwillbeintroducedthroughthisinterface.FilamentIongeneratedbyfilamentwillgivetheelectronimpacttothesampletoproducethesampleionization.IonsourceboxIonLens-Highion