仪器分析英文原版教案(13)

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1、GasChromatography(Chapter27)Twomajortypes¥Gas-solidchromatography(stationaryphase:solid)¥Gas-liquidchromatography(stationaryphase:immobilizedliquid)RetentionVolume:V1R4=2t4R3×FV1M4=2t4M3×Fretainednon-retainedaveragevolumetricflowrate(mL/min)Fcanbeestimatedbymeasuringflowrateexiting

2、thecolumnusingsoapbubblemeter(somegasesdissolvinginsoapsolution)butmeasuredVRandVMdependon¥pressureinsidecolumn¥temperatureofcolumnCEM333page15.1VRandVMdependonaveragepressureinsidecolumnColumnhasresistancetoflowAtinlet,P=high,F=lowö÷P×F=constantAtoutlet,P=low,F=highøPressuredropfa

3、ctorjusedtocalculateaveragepressurefrominletpressurePinletandoutletpressurePoutlet23[(Pinlet/Poutlet)-1]j=32[(Pinlet/Poutlet)-1]CorrectedRetentionVolume:00VR=j×tR×FVM=j×tM×FSpecificRetentionVolume:V0-V0273V=RM´gMs1T4column243correctionfortemperaturemassofstationaryphasepartitionrat

4、iocs/cmK273Vg=´rstationaryTcolumndensityofstationaryphaseVg-semi-usefulparameterforidentifyingspecieseluting-oftenscaleswithvaporpressure(constantpolarityanalytes)CEM333page15.2GCInstrumentation(Fig27-1):Carriergas:He(common),N2,H2Pinlet10-50psigF=25-150mL/minpackedcolumnF=1-25mL/m

5、inopentubularcolumnColumn:2-50mcoiledstainlesssteel/glass/TeflonOven:0-400¡C~averageboilingpointofsampleaccurateto<1¡CDetectors:FID,TCD,ECD,(MS)CEM333page15.3Sampleinjection:-directinjectionintoheatedport(>Toven)usingmicrosyringe(i)1-20mLpackedcolumn(ii)10-3mLcapillarycolumnFig27-3

6、-rotarysamplevalvewithsampleloopFig27-4CEM333page15.4Splitinjection:routinemethod0.1-1%sampletocolumnremaindertowasteSplitlessinjection:allsampletocolumnbestforquantitativeanalysisonlyfortraceanalysis,low[sample]On-columninjection:forsamplesthatdecomposeaboveboilingpoint-noheatedin

7、jectionportcolumnatlowtemperaturetocondensesampleinnarrowbandheatingofcolumnstartschromatographyCEM333page15.5GCDetectors:Need¥Sensitive(10-8-10-15gsolute/s)¥OperateathighT(0-400¡C)¥Stableandreproducible¥LinearresponseDesire¥Widedynamicrange¥Fastresponse¥Simple(reliable)¥Nondestruc

8、tive¥Uniformresponsetoalla