仪器分析课件

仪器分析木志坚AASFourier-TransformUV-VISGC-MSHPLCCourseObjectivesLecture:Discusstheoryandbackgroundfor1)physical/chemicalpropertiesmeasured2)originofphysical/chemicalproperties3)Instrumentationandnatureofresponse4)SignalprocessingandrelationshipbetweenreadouttopropertiesmeasuredLaboratory:Provideshands-onexperiencein1)relatinglecturematerialtopracticalanalysis2)operationandmeasurementsonrangeofinstruments3)establishmentofinstrumentalmethodsofanalysis4)exampleanalysestoillustratevalueoftechniqueTeachfundamentalsofInstrumentalanalysisChapter1IntroductionQualitative(定性)isthatmeasuredpropertiesindicatepresenceofanalyteinmatrix(基体).Quantitative(定量)isthatmagnitudeofmeasuredpropertiesisproportionaltoconcentrationofanalyteinmatrix.ClassificationofanalyticalmethodsSpeciesofinterestAllconstituentsincludinganalyteMatrix-analyte=concomitants(共存物)Oftenneedpretreatment-chemicalextraction,distillation,separation,precipitation1)ClassicalQualitative–identificationbycolor,indicators,boilingpoints,odorsQuantitative–massorvolume(e.g.gravimetric,volumetric)2)InstrumentalQualitative–identificationbymeasuringphysicalproperties(e.g.spectroscopy,electrodepotential,massspectra)Quantitative–measuringpropertiesanddeterminingrelationshiptoconc.(e.g.spectrophotometry,massspectrometry)Chapter1IntroductionThescienceandartofdeterminingchemicalcomposition,state,concentrationorstructureofmaterialswithinstrumentsbasedonphysicalorphysicochemicalpropertiesofaparticularelementorcompound.DefinitionofinstrumentalanalysisChemical/physicalinformationobservablesignalsInstrumentsChapter1Introduction1)Interactionofradiantenergywithmatter2)Electricalandelectrochemicalproperties3)Inter-phaseseparation4)OtherpropertiesPhysicalpropertiesusefulininstrumentalanalysisMechanicalpropertiesThermalpropertiesNuclearpropertiesExtensivepropertiesChapter1IntroductionClassificationofmaininstrumentalmethods1)OpticalmethodsAtomicMolecularAbsorption:spectroscopy(AAS)Emission:spectroscopy(AES)FluorescencespectroscopyUV-VISspectrophotometryIRspectroscopy2)ElectrochemicalmethodsElectricalpotentialPotentiometry(电位法)ElectricalchargeCoulometry(库伦法)ElectricalcurrentVoltammetry(伏安法):ElectricalresistanceConductometry(电导法)amperometry(安培法)polarography(极谱法)3)Inter-phaseseparationGaschromatography(GC)Liquidchromatography(LC)Ionchromatography(IC)4)OthermethodsThermalThermogravimetry(热重分析),Calorimetry(测热法)MasstochargeratioMassspectrometry(质谱法)RadioactivityIsotopedilution(同位素稀释法)Chapter1IntroductionBasicframeworkofinstrumentationEnergystimulusAnalyte(inmatrix)AnalyticalresponseDataencodedinformation1)Stimulus:monochromaticlight(单色光)energy2)Analyticalresponse:lightabsorptionDetector(general):devicethatindicateschangeinenvironmentTransducer(specific):devicethatconvertsnon-electricaltoelec.dataSensor(specific):devicethatconvertschemicaltoelec.data3)DataType:electricalcurrentDataprocessor:currentmeterReadout:meterscaleExample:SpectrophotometerChapter1Introduction1)Howreproducible?—Precision2)Howclosetotruevalue?—Accuracy/bias3)Howsmalladifferencecanbemeasured?—Sensitivity4)Whatrangeofamounts?—Dynamicrange5)Howmuchinterference?—SelectivityHowtochooseaninstrumentalmethod?Howgoodisameasurement?Chapter1IntroductionPrecision—IndeterminateorrandomerrorsAbsolutestandarddeviationRelativestandarddeviationStandarddeviationofmeanAccuracy—DeterminateorsystematicerrorBias=X–XtrueChapter1IntroductionSystematicerror—SourcesInhomogeneity(样品不均匀)–handling&storageContamination–samplingtoreagentsAdsorptiononsurfaceorvolatilizationUnwantedorincompletechemicalreactionsMatrixeffectsongenerationofanalyticalsignalIncorrectstandardsorcalibrationOperatorInstrumentsChapter1IntroductionRecognitionofsystematicerrorsReproducibilitygivesnoinformationonaccuracyMakecomparisonswithothermethodsCheckstandardreferencematerialsRunblanks(besurebackgroundissmallandreproducible)Whereistheaverageofsignaloutputofablank,sb(noise)isstddevofthefluctuationsoftheinstrumentoutputwithablank,kisagivencoefficientataspecifiedconfidencelevel(k=3byIUPAC)Chapter1IntroductionSensitivity(灵敏度)Detectionlimit(DLorLOD,检测限)or(Thelargerslopeofcalibrationcurve,themoresensitive)XLbks+=XbMinimumsignaloutputmeasured:bXXLbXDSs3==bSLODChapter1IntroductionDynamicrangeAtdetectionlimitwecansayconfidentlyanalyteispresentbutcannotperformreliablequantitation(定量化)Limitofquantitation(LOQ,定量限):k=10Limitoflinearity(LOL,线性限):WhensignalisnolongerproportionaltoconcentrationDynamicrangeChapter1IntroductionSelectivity(选择性)Noanalyticalmethodiscompletelyfreefrominterferencebyconcomitants.Bestmethodismoresensitivetoanalytethaninterferingspecies(interferents).MatrixcontainingspeciesA&B:Signal=SACA+SBCB+SignalblankSelectivitycoefficient:kB,A=SB/SAThevaluesofkvarybetween0(noselectivity)tolargernumber(veryselective)BasisofquantitativeanalysisismagnitudeofmeasuredpropertiesisproportionaltoconcentrationofanalyteSignal[c]orSignal=S[c]+SignalblankChapter1IntroductionCalibrationmethods(校准方法)Signal-Signalblank[c]=S[c]Chapter1IntroductionRelationshipbetweenChemicalAnalysisa