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 Maintenance Troubleshooting1630 1700 Q A GasChromatography一 Principle Theory二 Column三 Injector四 Detector Principle Theory PrincipleDistributionofsamplecomponentsbetweenthemobilegasphaseandthestationaryphase Somecomponentsinteractmorewiththestationaryphasecausingthemtomoveslowerthroughthecolumnandbecomeseparated Separationofsamplecomponents TheGCSystem CarrierGasInertHelium argon nitrogen hydrogen Choicedictatedbydetector cost availability Pressureregulatedforconstantinletpressure Flowcontrolledforconstantflowrate InjectorSampleintroduction vaporization Syringeinjection accurate reproducible Injectiontechniquesaresampledependent Column ColumnOven Accuratetemperaturecontrol 0 1 C Temperatureprogrammable Detector Respondstocomponents Universalorselectivedetection Chromatogram Plotofdetectorsignalversustime ComponentsappearaspeaksfrombaselineAllowsmeasurementofpeakretentiontimesandareas Qualitativeanalysis identityofcomponent Quantitativeanalysis amountofcomponent GCTheory ResolutionDegreeofseparationbetweentwopeaks Measureofpeakwidthanddistancebetweenpeaks Capillarycolumnhasgreaterresolutionthanpackedcolumn PeakShape IdealpeakshapeisaGaussiancurve StatisticaldistributionofMolecules ColumnSelectivity Solubilityversusvolatility Chemicalnatureofstationaryphase Chemicalnatureofsamplecomponents Vaporpressureofcomponents tR2 tR1 1 Separationisachievable ColumnSelectivity ColumnEfficiency Measureofpeakbroadening Quantitativelyexpressedasnumberofplates Vapor liquidequilibriumindistillation Fortheabovebubbble capcolumn thenumberofplate 3 Platetheory FactorsInfluencingColumnEfficiency A Eddydiffusion multipatheffect Dependsonsize shapeofpacking andhowwellcolumnwaspacked Negligibleforcapillarycolumns B Longitudinaldiffusion Moleculardiffusioningasphase Stronglydependentonflowrate C Resistancetomasstransfer Easeoftransferofsamplecomponentsfromgasphasetostationaryphase Stronglydependentonflowrateandamountofstationaryphase TheVanDeemterEquation Combinesthethreebandbroadeningeffects HEPT Heightequivalenttoatheoreticalplate HETP A B u Cu WhereA EddydiffusionB LongitudinaldiffusionC Resistancetomasstransferu CarriergaslinearvelocityLowHETP highcolumnefficiency Canbecalculatedifeffectivenumberofplatesisknown HETP Lcol Neff TheVanDeemterPlots Plotdeterminesoptimumlinearvelocity LossofeddydiffusionincapillarycolumnsresultsinlowerHETP CarrierGasAffectstheVanDeemterPlot N2 highestm w giveslowestHETP H2andHegiveflattercurvesathigherflowratesforfasteranalysistime PowerRequirements Separatecircuitswithreliableground Groundtoneutralpotentialmustnotexceed3V ACorDC Singlephase phaseneutral poweronly 15ampsfor99 132Vor8ampsfor198 264V Qualityofpower 120AC 8 V 60Hz 3Hz 220 240AC 8 V 50Hz 3Hz Freeofshortorlongdurationfluctuations PowerRequirements Powercordwiringandplugs CarrierGasSupplyandControl Dictatedbydetector Chromatographicgradegases highpurity Filteringsystem Catalystforoxygen Activecharcoalforheavyhydrocarbons Molecularsieveforwatervapor GasInletsandConnections Two stageregulators Low pressurestageratedforzeroto100psig Donotuseuncleanedtubing GasInletsandConnections Allgasesconnectto1 8 Swagelok fittingsonrearofinstrument InletDevices PackedColumnInjectorsVaporizessample Transferstoheadofcolumn Aluminumblockinjectoroven Heatercartridgeandprobe APackedColumnInjector CapillaryInjectors Smallersamplecapacity Specialtechniques split splitless on column Lowcarriergasflowrates Make upgasrequiredfordetector Specialhardware Septumpurge Splitterhardware Pressure flowregulation ACapillaryInjector GasSamplingValves Forusewithgaseoussamples Operatedmanuallyorautomatically Loadposition samplefillsloopasaknownamount Gassamplingvaleinloadposition Injectposition sampleisflushedfromloopintocolumnbythecarriergas Gassamplingvaleininjectposition Column ColumnMaterialsandConstruction Packedcolumns Short 2 3m wideboretubing Capillarycolumns long 60m narrowboretubing Allmaterialsshouldbethermallyandchemicallystable Thermallystable temperaturesneededforanalyseswillnotdecomposethecolumnmaterials Chemicallystable Temperatures freeofanalysiswillnotdecomposethecolumnmaterials Usechromatographygrade cleanmaterials PackedColumns Stainlesssteeltubingismostoftenusedbecauseitisinertandrigid Glass nickel andteflon linedstainlesssteelarealsoavailable moreinert ThepackingconsistsofasolidsupportcoatedwithaliquidphaseforGLCcolumns oraporoussolidforGSCcolumns Packcolumndimensions SolidSupport Servesasbaseforliquidphase Increasessurfaceareaavailabletosample Small uniformlysized porousparticles Highconcentrationofsilica Standardmeshsizes Diameterequivalentstomeshsize Example Mesh80 100meansthatalltheparticleswillpassthroughan80meshscreenbutnotthrougha100meshscreen An80meshscreenisonethathas80standarddiameterwiresperinch SolidSupport Silylation Surfacedeactivation Washingwithstrongacidremovesmetals Chemicaltreatment DMCS TMCS Finalpolaritycompatiblewithstationaryphase R SiOH CH3 2SiCl2 R SiOSi CH3 2ClR SiOSi CH3 2Cl CH3OH R SiOSi CH3 2OCH3Methylfunctionalgroupsreplacealcoholgroups LiquidPhases GLC Uniformlycoatedonthesolidsupport Recommendedloading2 10 byweight Non volatileliquids Selectivity separatingpower Varyinchemicalcomposition Cross sectionofapackedcolumn SolidAdsorbents GSC Porousadsorbents Requiresnoliquidphase Silicagel alumina molecularsieve Porouspolymerbeads Ethylvinylbenzenecross linkedwithdivinylbenzene Functionsassolidsupportandstationaryphase Availableinrangeofpolarities CapillaryColumns Stainlesssteel glass fusedsilica Flexiblebutmechanicallystrong Inert 0 05 0 80mmID Lengthsgreaterthan100mpossible 30mmostcommon Layerofpolyimideappliedtooutsidetofillflawsandstrengthen Innersurfaceundergoessilylation Stationaryphasecoatedoninnerwall StationaryPhase Coatedasathinuniformfilmoninnerwalls Similarincompositiontoliquidphaseinpackedcolumns WCOT Innersurfacecoatedwiththinlayerofstationaryphase PLOT Innersurfacecoatedwithporouslayerofsolidsupportoradsorbent SCOT Innersurfacefirstcoatedwithasolidsupport thenthestationaryphase StationaryPhase Cross sectionalviewofacapillarycolumn CoatingMethods Dynamicmethod pressure evaporation conditioning Staticmethod filling vacuumevaporation conditioning ColumnInstallation CuttingtheCapillaryColumn1 Threadnutandferruleovercolumn 2 Usesharpscoringtool 3 Inspectcutwitheyepiece Ajagged edgedcolumncandisruptcarriergasflowcausingtailingandpeakbroadening Installation Thecolumnshouldbeinsertedthemeasuredamountspecifiedforyourinjectoranddetector Ensurecarriergashasbeenflowingthroughcolumnsforatleast15 30minutes Slowly 5 min ramptoconditioningtemperature Conditioninitiallyfor 4hours Ifcontaminated conditioned20 Cbelowmaximumrecommendedcolumntemperature Normalrecommendedconditioningtemperature Tcond Tmax 2 Tapp 2 TappwhereTcond ConditioningtemperatureTmax MaximumrecommendedtemperatureforcolumnTapp Maximumtemperatureofyourapplication ColumnConditioning RangeandAttenuation Botharetimeprogrammable Range amplifiesoriginalsignal Rangesindicatelinearityofdetector e g FID 10 8 10 9 10 10 10 11 10 12 Attenuation Binaryattenuatorwithsettingsof1 2 4 1024 Dividestheoutputsignalbythechosenvalue ColumnDimensions ColumnLengthOnlylargelengthadjustmentsaffectresolution Packedcolumnsaretypically2 3m Capillarycolumnsmaybecuttothedesiredlength ColumnInternalDiameterPackedcolumnsfixedat2mmID Capillarycolumnsvaryfrom0 10 0 8mmID Affectscolumnefficiency retention capacity SmallerIdshavelowerbleedandlowercapacity IDSuggestions 0 25mmforsplit splitlessoron columninjection ifanalyteoverloadingisnotaproblem 0 32mmforsplitlessoron columninjectionwhenmoreconcentratedsamplesarebeinganalyzed 0 53mmifyouarereplacingapackedcolumnandareseparatingfewerthan30components Typicalcapillarycolumncharacteristics FilmThickness Amountofstationaryphasecoating Affectsretentionandcapacity Thickerfilmsincreaseretentionandcapacity Thinfilmsareusefulforhighboilers Standardcapillarycolumnstypically0 25 m 0 53mmIDcolumnstypically1 0 1 5 m Packedcolumnstypically 10 m ColumnCapacity Columncapacityisthemaximumamountofsamplethatcanbeinjectedontothecolumnwithoutsignificantpeakdistortion Columncapacityincreaseswith Filmthickness df Temperature Internaldiameter ID Stationaryphaseselectivity Ifexceeded resultsin Peakbroadening Asymmetry Leadingedgeortailing LiquidStationaryPhases Choiceofphasedeterminescolumnselectivity Hundredsofphasesavailable particularlyforpackedcolumns Manyphasemayhavemultiplebrandnames Stationaryphaseselectionforcapillarycolumnsismuchsimpler Likedissolveslike Usepolarphasesforpolarcomponents Usenon polarphasesfornon polarcomponents Polarityrepresentsseparationofcharge Presenceofdipolemoment SiloxaneBackbone Stationaryphasesubstitution ColumnBleed Seenasthenormalbackgroundsignalfromthedetector Bleediscausedbyabreakdownofthestationaryphase Bleedincreaseswithfilmthickness columndiameter length andtemperature Polarcolumnshavehigherbleed Bleedisexcessivewhenthecolumnisdamagedordegraded avoidleaks Avoidstrongacidsandbases Adheretomanufacturer srecommendedtemperaturelimits Strongacidsandbases TemperatureLimits LowerLimit Phasetakesonpropertiesofasolid islessefficient butundamaged IsothermalUpperLimit Highestrecommendedtemperatureforisothermaloperation ProgrammedUpperLimit Shouldonlybereachedforshortperiods typically20 Caboveisothermallimit Excessivepeaktailingandcolumnbleedarenoticeableonathermallydamagedcolumn Summary ChoosingaLiquidStationaryPhase Matchpolarityofsamplecomponentstophasechosen Non polarphasecolumnslastlonger chooseleastpolarphasethatgivesadequateseparation ForgeneralpurposeGC aslightlypolarphasesuchasVA 5iscommon Avoidphaseswithelementsthatrespondinyourdetector Usepolyethyleneglycolphasesforhydrogenbondingsamples Gasanalysesmayrequireasolidstationaryphase SolidStationaryPhases GSCisprimarilyusedforgaseoussamples Fewersolidsupportadsorptivesitestocausetailing Noliquidphasecolumnbleed Injector PackedColumnInjectors On columninjection Flash vaporization On ColumnLiquidsampleisinjecteddirectlyontotheheadofthecolumn Eliminatessamplelossduringvaporization Eliminatessamplelossduringtransferfrominjectortocolumn Allowsforthermallylabilecompounds Excellentquantitativeprecision Bestwithcleananddilutesamples Model1040 SandwichInjection Flushthesyringewithcleansolvent Expelsolventandretracttheplunger inair tothe1 0 Lmark Drawseveralmicrolitersofsampleintothesyringebarrel removesyringefromsamplevialandexpelsampleplug Retracttheplunger pullingtheneedleloadentirelyintothebarrelandnotethevolumeofthesampleplug Insertneedleintotheinjector injectthevolumeofthesampleplug Flash Vaporization Forconcentratedordirtysamples Columnconnectsatbottomofinjector Columnremainscompletelypacked Samplevaporizesintheglassliner Injectorshouldbeatleast50 Cabovethecolumnoventemperature Canbemodifiedforusewithlargeborecapillaries CapillaryColumnInjectors Requiresdifferenthardwareandtechniques Directinjection Split splitlessinjection On columninjection DirectInjection On ColumnorFlashVaporization Largebore 0 53mmID only Completesyringecontentstransferredtocolumn AllowsslowInjectionoflargevolume 2 L ofdilutesamples Relativelylowinjectortemperaturemaybeused Model1041 Model1061 Split SplitlessInjection Designedfornarrowtolarge borefusedsilicacolumns0 1mmto0 53mmID Operateineithermode splitorsplitless SplitAllowsonlyarepresentativefractionofthesampleintothecolumn Usedwhencomponentsofinterestarehighlyconcentrated SplitlessActslikeadirectinjector Depositsmostofthesampleonthecolumn Splitter Samplesarepresentativefractionthatcouldnotbemeasuredbysyringe Reproduciblesplitratios Samplevaporizesinaglassinsert Homogeneousvaporizedsamplepassesoverthesplitpoint columntip Buffervolumeprovidesexpansionspacetodecreaseviscositychanges Massdiscriminationmaybeaproblem SplitRatio vent columnflowcolumnflowSplitratiousedisdeterminedbysamplecomplexityandconcentration SeptumPurge2 5mL minofcarriergasdirectedacrossundersideofseptum Removesresidualsampleandsolvent Controlledbyafrittedrestrictororneedlevalve Usedinalldedicatedcapillaryinjectors S R Model1079 Pneumaticsof1079Injector a Split b Splitless InjectorInserts 1079injectorinsert SplitInjectionGuidelines Injectortemperatureshouldbeatleast20 Chigherthanthehighestboilingcomponentsforefficientandreproduciblevaporization Useafastinjectionspeedwithoutpreheatingneedleandremoveneedleimmediatelyfollowinginjection Anautosamplershouldbe1 Lorless Iftemperatureprogramming theinitialcolumnoventemperatureshouldbejustabovethesolventboilingpoint therampshouldbestartedimmediatelyafterinjection Becertaintheseptumpurgeisuncappedandsetto2 5mL min SplitlessInjectionGuidelines 1 Switchtosplitlessmode Allinjectorflowwillbethroughcolumnandseptumpurge 2 Setinjectortemperatureattheboilingboilingofthehighestboilingcomponent 3 Injectsampleslowlyusingsandwichtechnique Preheatneedleintheinjector0 05min Useaninjectionrateof1 0 L sec Leavesyringeininjectionportseveralsecondstoensurecompletevaporization 4 Startcolumnoven20 Clowerthansolventboilingpoint holdfor1min rampat30 C minto40 60 Cabovesolventboilingpointandcontinueprogramasrequiredforthesample 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 Detectivityof 10pg Linearrangeof107 Easeofuse Destructive Responsedependsonnumberofcarbonatomsandamountofsubstitution FID FID Universaldetectorfororganicmolecules Destructivedetector burnssample Theory Apotentialisappliedbetweentheflametipandthecollector electrodes Organiccompoundsareburnedintheflame 2000 F 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 sample currentloss Cellispulsedatthefrequencythatproducesacurrentidenticaltoareferencecurrentinthedetectorelectronics Frequencyofpulsesisincreasedtorestorecurrentwhenelectroncap