原子吸收光谱.pdf
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1、 原子吸收光谱分析培训教材原子吸收光谱分析培训教材(基础知识与基本操作基础知识与基本操作)珀金埃尔默仪器(上海)有限公司 张扬祖 编 原子吸收光谱分析原子吸收光谱分析原子吸收光谱分析原子吸收光谱分析应用与仪器操作培训应用与仪器操作培训应用与仪器操作培训应用与仪器操作培训PerkinElmer Shanghai 张扬祖编課程內容課程內容課程內容課程內容1.1.原子吸收光谱分析的基本知识原子吸收光谱分析的基本知识原子吸收光谱分析的基本知识原子吸收光谱分析的基本知识1.11.1原子吸收光谱分析原理原子吸收光谱分析原理原子吸收光谱分析原理原子吸收光谱分析原理1.21.2原子吸收光谱仪器的组成原子吸收光
2、谱仪器的组成原子吸收光谱仪器的组成原子吸收光谱仪器的组成1.31.3原子吸收光谱分析中的干扰及其消除原子吸收光谱分析中的干扰及其消除原子吸收光谱分析中的干扰及其消除原子吸收光谱分析中的干扰及其消除1.41.4原子吸收光谱分析的准确性保证原子吸收光谱分析的准确性保证原子吸收光谱分析的准确性保证原子吸收光谱分析的准确性保证2.2.原子吸收光谱仪器操作原子吸收光谱仪器操作原子吸收光谱仪器操作原子吸收光谱仪器操作2.12.1火焰法操作火焰法操作火焰法操作火焰法操作2.22.2石墨炉法操作石墨炉法操作石墨炉法操作石墨炉法操作2.32.3操作过程中的安全注意事项操作过程中的安全注意事项操作过程中的安全注意
3、事项操作过程中的安全注意事项2.42.4仪器测定条件优化仪器测定条件优化仪器测定条件优化仪器测定条件优化2.52.5仪器维护保养仪器维护保养仪器维护保养仪器维护保养2.62.6测定数据处理测定数据处理测定数据处理测定数据处理现代无机元素分析的四种手段现代无机元素分析的四种手段现代无机元素分析的四种手段现代无机元素分析的四种手段1.1.原子吸收光谱分析原子吸收光谱分析原子吸收光谱分析原子吸收光谱分析(AAS)AAS)2.2.原子发射光谱分析原子发射光谱分析原子发射光谱分析原子发射光谱分析(ICPICP-OES)OES)3.3.原子荧光光谱分析原子荧光光谱分析原子荧光光谱分析原子荧光光谱分析(AF
4、S)AFS)4.4.等离子体质谱等离子体质谱等离子体质谱等离子体质谱(ICPICP-MS)MS)Origins of Atomic SpectraOrigins of Atomic Spectra+eeeE=hvLightExcitedStatesDecay and Emission+eMoM*+Eback to ground state+E-E MoLightExcitation+eMoM*+Eexcited electron+EnergyPrinciple of Atomic SpectroscopyPrinciple of Atomic SpectroscopyHHeLiMEnergyE
5、mission(e)Absorption(a)IonizationAbsorption(a)Emission(e)BeGround stateExcitation levelIonizationV:Ionizsation potentialEn,Em:Excitation potential E=En-Em=h EnEmVAAAA与与与与ICPICP-OES,OES,ICPICP-MSMS的检出限的检出限的检出限的检出限之比較表之比較表之比較表之比較表Atomic SpectroscopyAtomic Spectroscopy EMISSIONEMISSIONMMo o+heat +heat
6、MM*MMo o+light+light ABSORPTIONABSORPTIONMMo o+light +light MM*原子吸收光谱分析原理原子吸收光谱分析原理原子吸收光谱分析原理原子吸收光谱分析原理(1)(1)pp锐线光源与连续光源锐线光源与连续光源锐线光源与连续光源锐线光源与连续光源A=log(IA=log(I0/It)0/It)A=log(I0+IA=log(I0+I)/(It+I)/(It+I)Atomic AbsorptionAtomic Absorptionsample absorptionsource emission0.003 nm0.001 nm原子吸收光谱分析原理原子
7、吸收光谱分析原理原子吸收光谱分析原理原子吸收光谱分析原理(2)(2)pp相对测量方式相对测量方式相对测量方式相对测量方式pp基态原子吸收基态原子吸收基态原子吸收基态原子吸收pp溶液状态进样溶液状态进样溶液状态进样溶液状态进样pp元素总量测定元素总量测定元素总量测定元素总量测定可供选用的原子吸收测定技术可供选用的原子吸收测定技术可供选用的原子吸收测定技术可供选用的原子吸收测定技术火焰原子吸收法火焰原子吸收法火焰原子吸收法火焰原子吸收法(AIRAIR-C2H2,N2OC2H2,N2O-C2H2)C2H2)石墨炉原子吸收法石墨炉原子吸收法石墨炉原子吸收法石墨炉原子吸收法氢化物发生原子吸收法氢化物发生
8、原子吸收法氢化物发生原子吸收法氢化物发生原子吸收法动注射动注射动注射动注射-火焰原子吸收法火焰原子吸收法火焰原子吸收法火焰原子吸收法动注射动注射动注射动注射-石墨炉原子吸收法石墨炉原子吸收法石墨炉原子吸收法石墨炉原子吸收法动注射测汞法动注射测汞法动注射测汞法动注射测汞法火焰原子发射法火焰原子发射法火焰原子发射法火焰原子发射法空气空气空气空气-乙炔火焰的应用乙炔火焰的应用乙炔火焰的应用乙炔火焰的应用特点特点特点特点:安全安全安全安全,稳定稳定稳定稳定,灵敏高灵敏高灵敏高灵敏高可测元素可测元素可测元素可测元素:Ag,As,Au,Bi,Ca,Ag,As,Au,Bi,Ca,CdCd,Co,Cr,Cs,
9、Cu,Fe,Hg,In,Co,Cr,Cs,Cu,Fe,Hg,In,Ir Ir,K,Li,Mg,K,Li,Mg,MnMn,Na,Ni,Na,Ni,PbPb,Pd,Pt,Pd,Pt,RbRb,RhRh,RuRu,SbSb,Se,Se,TcTc,Te,Te,TlTl,ZnZn共共共共3232个元素个元素个元素个元素一氧化二氮一氧化二氮一氧化二氮一氧化二氮-乙炔火焰的应用乙炔火焰的应用乙炔火焰的应用乙炔火焰的应用特点特点特点特点:温高温高温高温高,化学干扰少化学干扰少化学干扰少化学干扰少,灵敏较低灵敏较低灵敏较低灵敏较低可测元素可测元素可测元素可测元素Al,B,Al,B,BaBa,Be,Be,DyDy
10、,ErEr,EuEu,GaGa,GdGd,GeGe,HfHf,Ho,La,Lu,Mo,Ho,La,Lu,Mo,NbNb,NdNd,Os,P,Pr,Re,Sc,Os,P,Pr,Re,Sc,SiSi,SmSm,SnSn,SrSr,Ta,Tb,Ti,Tm,U,V,W,Y,Ta,Tb,Ti,Tm,U,V,W,Y,YbYb,Zr Zr 共共共共3636个元素个元素个元素个元素石墨炉原子吸收技术石墨炉原子吸收技术石墨炉原子吸收技术石墨炉原子吸收技术特点特点特点特点:灵敏高灵敏高灵敏高灵敏高,检出限低检出限低检出限低检出限低,样品用少样品用少样品用少样品用少,自动化程高自动化程高自动化程高自动化程高可测元素
11、可测元素可测元素可测元素:Ag,Al,As,Au,B,Ag,Al,As,Au,B,BaBa,Be,Bi,Ca,Be,Bi,Ca,CdCd,Co,Cr,Cs,Cu,Co,Cr,Cs,Cu,DyDy,ErEr,EuEu,Fe,Fe,GaGa,GdGd,GeGe,Hg,Hg,In,In,Ir Ir,K,La,Li,Mg,K,La,Li,Mg,MnMn,Mo,Na,Mo,Na,NdNd,Ni,Os,P,Ni,Os,P,PbPb,Pd,Pt,Pd,Pt,RbRb,RhRh,RuRu,SbSeSbSe,SiSi,SmSm,SnSn,SrSr,Te,Ti,Tm,U,V,Y,Te,Ti,Tm,U,V,Y,Yb
12、Yb,Zn ,Zn 共共共共5656个元素个元素个元素个元素空气空气空气空气-乙炔火焰发射的应用乙炔火焰发射的应用乙炔火焰发射的应用乙炔火焰发射的应用特点特点特点特点:无需灯光源无需灯光源无需灯光源无需灯光源,灵敏高灵敏高灵敏高灵敏高可测元素可测元素可测元素可测元素:Cs,K,Na,P,Cs,K,Na,P,RbRb,Se,Se,TcTc氢化物形成原子吸收测定氢化物形成原子吸收测定氢化物形成原子吸收测定氢化物形成原子吸收测定1.1.可测元素可测元素可测元素可测元素:As,Se,As,Se,SbSb,Bi,Bi,SnSn,Te,Hg,Te,Hg2.2.分析性能特点分析性能特点分析性能特点分析性能特
13、点:灵敏高灵敏高灵敏高灵敏高,检出限低检出限低检出限低检出限低,基体干扰少基体干扰少基体干扰少基体干扰少3.3.灵敏度与测定元素的价态相关灵敏度与测定元素的价态相关灵敏度与测定元素的价态相关灵敏度与测定元素的价态相关原子吸收光谱仪的组成原子吸收光谱仪的组成原子吸收光谱仪的组成原子吸收光谱仪的组成12345Sample(1)Light source(hollow cathode lamp)(1)Light source(hollow cathode lamp)(2)Sample cell/Atom reservoir(flame or furnace)(2)Sample cell/Atom re
14、servoir(flame or furnace)(3)Light separation(monochrometer)(3)Light separation(monochrometer)(4)Light measurement(detector)(4)Light measurement(detector)(5)Signal processing(computer/software)(5)Signal processing(computer/software)Typical AA Spectrometer ComponentsMonochromatorDetectorSample CellLig
15、ht SourceResultsChopperE Electrodelesslectrodeless D Discharge ischarge L LampampLight SourceHollow Cathode Lamp+-Ne or ArFill GasEnd WindowAnodeCathodeHollow Cathode LampEmission Process+-+-+-+-1.Ionization2.Sputtering3.Excitation4.EmissionNeoNe+Ne+MoNe+MoM*M*MoLightConsiderations with EDLsAdvantag
16、es?Lower gain?Higher absorbances?Better sensitivity?Longer lifetime?Greater intensityDisadvantages?Require warm-up?May require separate power supplyAtomic Absorption SpectroscopyAtomic Absorption SpectroscopyppTypically heat is used to break molecular bondsTypically heat is used to break molecular b
17、ondsCaCaClClClClCaCaClClClClGraphite Furnace AAGraphite Furnace AAFlame AAFlame AAPrinciple of Flame Atomic Absorption(FLAAS)1ppm2ppmElement:CdWave length:228.8 nmSlit:0.4 nmAbsorbanceProblems of FLAAS-Poor sensitivity.-Not multi-element.-Narrow dynamic range.(Atomic Absorption Spectrometer)Flammabl
18、e gas Inflammable gasDetectorSlitSlitGrating driven by motorHollow Cathode lampSampleFlameProcess in a Flame AAProcess in a Flame AADrainNebulizationSolutionSolidVaporizationMAMo+AoAtomizationMoM*ExcitationM*M+e-IonizationBurner AssemblyBurner AssemblyNew corrosion resistant New corrosion resistant
19、nebulizernebulizer designdesignppHigh Sensitivity designHigh Sensitivity designppOne design for both airOne design for both air-acetylene and nitrous acetylene and nitrous oxideoxideppUses ceramic impact Uses ceramic impact beadbeadppSample tubing Sample tubing connected via a screw connected via a
20、screw fitting for easy fitting for easy replacementreplacementBurner Head SelectionBurner Head Selection 10 10-cm head:general purpose for aircm head:general purpose for air-acetylene acetylene operationoperation 5 5-cm head:for nitrous oxide operation or short cm head:for nitrous oxide operation or
21、 short path length airpath length air-acetyleneacetylene 3 3-slot:high dissolved solids for airslot:high dissolved solids for air-acetylene acetylene operationoperationTemperature Distribution in a Temperature Distribution in a MassmanMassman-style style AtomizerAtomizerFork PlatformFork PlatformInt
22、egrated PlatformIntegrated PlatformMassmanMassman-style Furnacestyle FurnaceTemperature Distribution in a TransverselyTemperature Distribution in a Transversely-Heated AtomizerHeated AtomizerTHGA TubesTHGA TubesOpen End and End CapOpen End and End CapTHGATHGAStandard and End Cap TubesStandard and En
23、d Cap Tubes00.10.20.30.40.500.10.20.30.40.5Integrated AbsorbaceAgCoCrPbPb*SeSe*VAgCoCrPbPb*SeSe*VStandardStandardEnd-capEnd-cap*with Matrix ModifierSingleSingle-beam Configurationbeam ConfigurationMonochromatorHollowCathode LampDetectorRotatingChopperSampleBeamDouble-beam ConfigurationMonochromatorD
24、etectorReference BeamSampleBeamHollowCathode LampRotatingChopperTraditional GratingEchelle GratingIncident Light(all wavelengths)Echelle GratingAngle of Incidence()m=0(simple reflection)(all wavelengths)m=1=250nmm=2=250nmm=1=600nmm=50=600nmm=121=250nmm=119=250nmPerpendicular to face of gratingAngle
25、of Diffraction()m=diffraction order number=wavelengthFunction of the Monochromator?Disperse polychromatic light into its various wavelengths?Allows for the isolation of specific wavelengthsPMTPMTAAnalystAAnalyst 700 and 700 and AAnalystAAnalyst 800 800 Customized SolidCustomized Solid-State Detector
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