GasChromatographyPrelab气相色谱预习（PPT）

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1、GASCHROMATOGRAPHYORGILABDr.W.J.KELLYTHEGASCHROMATOGRAPHTHEGASCHROMATOGRAPHAgasmixture,calledtheMobilePhase,composedofaninert“carrier”gas(usuallyHelium)andvariousotherchemicalcomponentsinthevaporphaseintroducedattheInjectonPortpassthroughanon-movingmaterial,calledthe...StationaryPhase

2、,usuallytightlypackedintoacoppertubecalledtheColumn…whichseparatesthegasstreamintoitsparticularcomponentsbasedonhow“quickly”theymovethroughthestationaryphase.Thecomponentsreacha...Detectoratdifferenttimes,thedetectorgeneratesanelectricalsignalwhichissenttoa...Recordertorecordthesigna

3、l.Sincemanychemicalsubstancesaresolidsorliquidsatroomtemperature,thestationaryphase-mobilephasemustbeheatedtohighertemperatureinorderto“vaporize”thecomponentsofthemobilephase.Thusanexternalheatingdeviceor...Ovenisneeded.Thetemperatureoftheovenneednotbeabovetheboilingpointsofthecompon

4、entsbutratherabovethe“dewpoint”oftheleastvolatilecomponentTHEGCPROCESSTHESTATIONARYPHASEThemobilephasecanbeseparatedoutbythestationaryphasesthroughseveraldifferentprocesses.ThetwomostcommonprocessesareLiquid-PartitionChromatographyandAdsorptionChromatography.Wewillinitiallyconsiderth

5、eformercase.InLiquid-PartitionChromatography,thestationaryphaseconsistsofaveryporous,inert,finelypoweredmaterialcalledtheSolidSupport.ThesolidsupportiscoatedwithathinfilmofmaterialcalledtheLiquidPhase.Mostliquidphasesareveryhighboilingliquids,somearewaxesatroomtemperature.THESEPARATI

6、ONPROCESSAsthemobilephasepassesthroughthestationaryphase,thedifferentcomponentsofthemobilephasewilldissolveintotheliquidfilmofthestationaryphase.Thesolubilityofthegassesintheliquidphasesdependsonanumberoffactors,butoneofthemostimportantisthevolatilityoftheliquidfromwhichthecomponentv

7、apordrives.Gassesfromlowboilingliquidswillspendlesstimedissolvedintheliquidphase,whereasgassesfromlessvolatileliquidswillspendmoretimeinsolutionwiththeliquidphase.Thelesstimeagasspendsdissolvedintheliquidphases,themoretimeitspendsflyingalongwiththecarriergas.Thusitmovesthroughthestat

8、ionaryphasem