瓦里安系列7-瓦里安气相层析仪教材(繁体).ppt

氣相層析儀基礎課程,講員:張世春E-mail:kyle.chang日期:1999年7月15日主辦:美商亞洲瓦里安科技(股)臺灣分公司,課程表,0930-1030:GC基本原理I1030-1050:休息1050-1200:GC基本原理II1200-1300:午餐時間1300-1410:軟體操作I,1410-1420:休息1420-1530:軟體操作II1530-1550:休息1550-1630:Maintenancetherampshouldbestartedimmediatelyafterinjection.Becertaintheseptumpurgeisuncappedandsetto2-5mL/min.,SplitlessInjectionGuidelines,1.Switchtosplitlessmode.Allinjectorflowwillbethroughcolumnandseptumpurge.2.Setinjectortemperatureattheboilingboilingofthehighestboilingcomponent.3.Injectsampleslowlyusingsandwichtechnique.Preheatneedleintheinjector0.05min.Useaninjectionrateof1.0L/sec.Leavesyringeininjectionportseveralsecondstoensurecompletevaporization.4.Startcolumnoven20Clowerthansolventboilingpoint,holdfor1min.,rampat30C/minto40-60Cabovesolventboilingpointandcontinueprogramasrequiredforthesample.5.Useasamplingtimeof0.5-1.0minutes.Theinjectoristhenswitchedtosplitmodetoflush.Theventflowshouldbesettoatleast50mL/min.6.Makesuretheseptumpurgeisuncappedandsetto2-5mL/min.,SPIInjector,Detector,TheUniversalDetectors,TCDOneoffirstGCdetectors,1946.Measureschangesinthethermalconductivityofthesamplegasstream.Thermalconductivity-flowofheatfromahotbodytoacoolerbody.,TCDCELL,Twoparallelgasstreams,sampleandreference.Wheatstonebridgecircuitisusedtocomparetheresistanceofthetwostreams.Effectsofvariationinflowrate,pressure,andelectricalpowerareminimized.,ThermalConductivityofGases,Thesmallerthemolecule,thehigherthespeedandthermalconductivity.H2andHe,beingthesmallestmolecules,gavethermalconductivities6to10timesthatofmostorganiccompoundsorinorganicgases.H2orHearethemostcommoncarriergases;N2orArarealsoacceptable.,FID,MostcommonGCdetector.-Universalresponsetocarboncontainingcompounds.-Detectivityof10pg.-Linearrangeof107.-Easeofuse.Destructive.Responsedependsonnumberofcarbonatomsandamountofsubstitution.,FID,FID,Universaldetectorfororganicmolecules.Destructivedetector-burnssample.Theory:Apotentialisappliedbetweentheflametipandthecollector(electrodes).Organiccompoundsareburnedintheflame(2000F).Ionicintermediatesandelectronsareformedbetweentheelectrodes.Chargedspeciesareattractedtoandcapturedbythecollector.Ioncurrentisamplifiedandrecorded.,Response,Numberofionsisproportionaltothenumberofcarbonatoms(C-Hbonds).Functionalgroupssuchascarbonyl,alcohol,halogen,andamineproducefewerionsornoneatall.InsensitivetoinorganicgasesH2O,CO2,SO2,andNOx.FlamePlumbedwithairandhydrogen.Electricallyignitedatcontrolledflowrates(heatedcoil).Invisibleflame-unlesscontaminated.,FuelGases,H2typicallysetat1:1withcarrierflowrate(orcarrier+makeup).Airissetat10timestheH2flow.Highairflowandhotdetectortowerremovesexcesswatervapor.,FlowratedependencyoffuelgasesforFID,TheSelectiveDetectors,ECDNon-destructive.Sensitivetohalogens,peroxides,quinones,organometallics,andnitrogroups.Insensitivetoamines,alcohols,andhydrocarbons.Narrowlinearrange-103.,ECDOperation,particlescauseionizationofcarriergasproducingacloudofelectronswithinthecell.Whenanelectronabsorbingspeciesenterscell,thecurrentdecreasesbecausetheelectroncaptureresultsinfewerelectrons.N2+e-e-+samplecurrentloss,Cellispulsedatthefrequencythatproducesacurrentidenticaltoareferencecurrentinthedetectorelectronics.Frequencyofpulsesisincreasedtorestorecurrentwhenelectroncapturingspeciesispassingthrough.Signal=Fs-FoWhereFs=samplefrequencyFo=referencefrequency,ECDCurrent,TSD,Thermionicspecificdetector.Rugged,simpledesign,similartoFID.Selectivetonitrogenandphosphorus.500timesmoresensitivetoPthantheFID.50timesmoresensitivetoNthantheFID.Applicationsincludepesticides,petroleumandfossilfuels,foodsandflavors,andpharmaceuticals.,TSD,FuelGases,Pneumaticsmustbeflowcontrolled-optimizationstronglydependsonH2flow.(H2:4-4.5ml/min,Air170ml/min)TSDBeadCeramicbeadinpregnatedwithRb2SO4.Beadinkeptat600-900Cduringanalysis.-Temperaturedeterminesdetectorsensitivity,backgroundcurrent,andbeaklifetime.CollisionsbetweenalkaliatomsandNorPcontainingmoleculescausechargetransferreactions.Reactionsresultinalkalications(+)andNorPanions(-).Cationsreturntobeadwhileanionsmigratetocollector.,OptimizingTSD,1.OptimizeN:Cselectivity.Setapproximateflowrates.Increasecurrentuntilbeadis600-800C(dullorange).ReduceH2flowuntilrelativearearesponseofazobenzenetoheptadecaneis4.5:1.C6H5N=NC6H5azobenzeneCH3-(CH2)15-CH3heptadecane2.theaboveprocedurealsooptimizesP:Cselectivity.3.Optimizesensitivitybyadjustingbeadcurrent.IfH2wasdecreasedduringselectivityoptimization,increasebeadcurrenttorestorebeadtemperature.,PFPD,Flamephotometricdetector.Selectivetosulfurorphosphorous.Applicationsincludedetectionofpollutantsinwaterandair,analysisofpesticidesandfossilfuelproducts.,PFPD,PFPDOperation,AfilterchangeisrequiredforswitchingbetweenPandSdetection.HeorN2isrecommendedforcarriergas.Detectortemperatureshoul