檢測器基本原理課件

GeneralOverviewofDetectorSystemsDanielaCavagninoGeneralOverviewofDetectorSDetectorsclassificationUniversalTheyrespondtoeverythingelutingfromthecolumnTCDPDD(FID)SelectiveTheymaybeelementselective,structure/functionalgroupselectiveorselectivetootherpropertiesFID(verybroad

selectivity)ECDPIDPDDSpecificTheyaresoselectivetodistinguishparticularstructuresorelementsNPDFPDDetectorsclassificationUniverConcentrationvsMassdependentresponseCommonconc.dependent:TCDPIDPDDECDCommonmassdependent:FIDNPDFPDNon-DestructivevsDestructiveCommonnon-destructive:TCDPIDPDDECDCommondestructive:FIDNPDFPDDetectorsclassificationConcentrationvsMassdependenDetectorResponseCharacteristicsSensitivityDetectorefficiencytoconvertthesampleinanelectricalsignalNoiseShortterm:highfrequencybaselinefluctuationLongterm:lowfrequencybaselineperturbationDynamicRangeRangeofsampleconcentrationforwhichthedetectorcanprovideadetectablesignalvariationwithanalyteamountSelectivityTheratioofthedetectorsensitivitiesofagivencompoundoverapotentiallyinterferingcompoundMinimumDetectabilityAmountofsampleinwhichthepeakheightis3timesthenoiseheight(S/N=3)DetectorResponseCharacteristDetectorResponseCharacteristics

SensitivityandMinimumDetectabilityFIDsensitivity:S===coulomb/g=FPDsensitivityforsulfur:S=*=uV/(gS/s)2MDA===g/secRF(ResponseFactor)=MDA==gS/secpeakareasampleweightA*secgpeakareaSamountPW?Samount3NSA*gA*secpeakareaamount3NSpeakheightmassraten-1?DetectorResponseCharacterist

DynamicandLinearRangeDynamicrange:overwhich

anincrementalchangeinthe

amountofcompoundsinthe

detectorvolumeproducesa

measurableincremental

changeinthedetectorsignalLinearrange:overwhich

theresponsedeviationisless

than5%DetectorResponseCharacteristicsDynamicandLinearRangeDyFlameIonizationDetectorUniversalresponseIonizationdetectionMassdetectorDestructiveFlameIonizationDetectorUnivFlameIonizationDetectorHydrogenismixedwithgasstreamatbottomofjetandairoroxygenissuppliedaxiallyaroundthejetHydrogenflameburnsatthetip,whichalsofunctionsascathodeanditiselectricallyinsulatedfromthebodyCollectorelectrodeisabovetheburnertipFlameIonizationDetectorHydroFlameIonizationDetectorPrincipleofoperationCombustionof

organiccompoundsina

oxidizingflameCH+OCHO++e-Electricfieldbetween

thejetandthecollector

electrodeVoltage-300VCollectionofthe

ionsgeneratedinto

theflameCurrentpAAgoodcombustionstepistheprevailingfactortogetthebestperformancesFlameIonizationDetectorPrincFlameIonizationDetectorItrespondstoallorganiccompoundsexceptforformicacidResponseisgreatestwithhydrocarbonsanddecreaseswithsubstitutionSensitivityhighduetolownoiselevelNoresponsetowater,permanentgases,andinorganiccompoundssimplifiestheresolutionofcomponentsinanalysisofaqueousextractsandinairpollutionstudiesSuitableforfastandultrafastGCapplicationsFlameIonizationDetectorItrFlameIonizationDetectorTechnicalSpecifications

Operatingtemperaturelimit 450°CwithceramicjetLinearrange betterthan106

Minimumdetectableamount 3x10-12gC/sInputrange 0to10-6AInputattenuation 4steps(100-101-

102-

103)Electrodepolarizationvoltage -300VTimeconstant 6ms@63.2%Acquisitionrate upto300HzFlameIonizationDetectorTechnFlameIonizationDetectorStandardOperatingProcedure(SOP)C12C14C16AreaCounts>4000000C12=6877493C14=6790762C16=6988181FlameIonizationDetectorStandFlameIonizationDetectorMDLCalculation(C12)C12C14C16V=1.6uL@20ng/uLMassC12=32ng%C=84.7%MassC=27.1ngC12A=6877493(0.1uV*s)MDL=3N/S

S=Area(uV*s)/mass

MDL=48(uV)*27.1(ngC)/687749.3(uV*s)=0.00189ngC/s=1.89pgC/sNoise16uVFlameIonizationDetectorMDLCElectronCaptureDetectorSelectiveresponseNon-destructiveIonizationdetectorprincipleConcentration-dependentdetectorRadioactivesource63Ni(10mCiactivity)Displacedcoaxial-cylindergeometryElectronCaptureDetectorSelecPrinciplesofdetectionElectronCaptureDetector---e-e-+++-MMMABAB_+*+N2 +N2++e-*+Ar +Ar++e-+Ar*Ar*+CH4 Ar+e-+CH4+dissociative-capturemechanismAB+e- A·+B-nondissociativemechanismAB+e- AB-sidereactionsC+e- C-N2++e- neutralsAB-+N2+ neutralsPrinciplesofdetectionElectrElectronCaptureDetectorPulsedvoltage[e-]V500TTime(s)w=0.11sPULSEvoltageDCvoltageElectronCaptureDetectorPulse

ElectronCaptureDetectorConstantcurrentmethodI=Ke-]f+-Iff=constI=constElectronCaptureDetectorConsConstantcurrentmethodModulationofPulseFrequencyioncurrent=electronsconcentrationxpulsefrequencywithnosample freq.=f°withelectronegativesample freq.=fssignaloutput=fs-f°=sampleconcentrationElectronCaptureDetectorConstantcurrentmethodModulatElectronCaptureDetectorRadioactivesource: Nickel63–370MBq(10mCi)Cellvolume 450LOperatingtemperaturelimit: 400°CMinimumdetectableamount: 10fgoflindaneLineardynamicrange: 104(argon/methane)

103(nitrogen)Operationmode: constantcurrentpulse-modulatedmodeReferencecurrent: 0to3nA(0.1nAsteps)Pulseamplitude: 5to50Vneg.Pulsewidth: 0.1s(argon/methane),

0.5s,1s(nitrogen)TechnicalSpecificationsElectronCaptureDetectorRadioElectronCaptureDetectorMolecularfeaturesgoverningtheresponseofECDLowresponseforalcohols,amines,phenols,aromaticsandvinyl

typefluorinatedhydrocarbonsHighresponseforhalocarboncompounds,nitroaromatics,and

conjugatedcompoundscontainingtwogroupswhichindividually

arenotstronglyelectronattractingbutbecomesowhen

connectedbyspecificbridgesResponsetowardsthehalogensdecreasesintheorderI>Br>Cl>FElectronCaptureDetectorMolecElectronCaptureDetectorMolecularfeaturesgoverningtheresponseofECDMultiplesubstitutionwithsimpleelectronattractinggroupsor

atomsmayincreasethemolecularabsorptionbyanamountmuch

greaterthanexpectedofasimpleadditiveeffectTheabsorptionconferredbyasimpleelectrophoricgroupisalso

sensitivetothepositioninthemoleculeSomeinorganiccompoundsareelectronabsorbers,ascarbon

disulfide,ozoneandtheoxidesofnitrogenElectronCaptureDetectorMolecElectronCaptureDetectorRelativesensitivityEthaneBenzene 1ButanolAcetoneChlorobutane 1-102Chlorobenzene1,2-dichlorobenzeneAntracene 102-104ChloroformNitrobenzene 104-105CarbontetrachlorideDinitrophenolDiethyloxalate 105-106DihydropyridineInfluenceofdetectortemperatureDetectionlimit(x10-9g)CCl4 0.010.010.01CHCl31.00.10.05CH2Cl21000408CH2ClCH2Cl1000201

80°C227°C350°CElectronCaptureDetectorRelatElectronCaptureDetectorRelativeresponseofhalocarbonsCF3CF2CF3 1.0CF3Cl 3.3CF2=CFCl 100CF3CF2Cl 170CF2=CCl2 670CF2Cl2 3x104CHCl3 3.3x104CHCl=CCl2 6.7x104CF3Br 8.7x104CF2ClCFCl2 1.6x105CF3CHClBr 4.0x105CF3CF2CF2I 6.0x105CF2BrCF2Br 7.7x105CFCl3 1.2x106ElectronCaptureDetectorRelatg-LINDANEMDA=10fgwithS/N=3ALDRIN(15pg)HEPTACHLOR(10pg)g-LINDANE(10pg)x2x64ECDperformanceMinimumDetectableAmountg-LINDANEMDA=10fgwithSBestconditionsforECDsensitivity

ECDsensitivityisaffectedbythefollowingfactors:

Referencecurrent

Thehigheristhereferencecurrent,thegreateristhesignalresponsebut

alsothebaselinenoise.TheS/Nrationeedstobedeterminedfor

sensitivityevaluation

Ionizinggas(makeup)

TheECDisaconcentration-dependentdetector.Theloweristhemakeup

flowrate(upto15-20mL/min),thehigheristheresponse.

Argon/methaneasmakeupgasallowstooperateatlowerfrequencies

whileusinghigherreferencecurrentsetting

Detectortemperature

Forsomecompoundsthesensitivitywillincreasewiththecelltemperature

(dissociativemechanismofreaction)BestconditionsforECDsensitECDperformanceLinearityECDperformanceLinearityBestconditionsforECDlinearity

ECDlinearityisverydependantuponseveralfactors:

ECDconditions

PulseVoltage:lowestisbetter(upto15V)accordingtotheoutputfreq.

Basefrequency:mustbearound1KHz

ReferenceCurrent:itcanbereducedto0.7-0.8nAifnecessary

Ionizinggas(makeup)–Argon/methane:assurethewidest

linearityrange

Nitrogen:shouldbeusedunderclean

conditionswith0.5usofPulseWidth

Inbothcasestheflowratecanbeincreasedto40-45mL/minformaintainingalowbasefrequency

Carriergas–Hydrogen:linearrangeuptoabout100pg

Helium:sligthlybetterthanhydrogen

Nitrogen:linearrangeshifteduptoabout200pgThecompletesystemincludingthegassupplylinesandgaseshavetobeverycleantoachievealowbasefrequencyBestconditionsforECDlinearElectronCaptureDetectorStandardOperatingProcedureSOPLindaneAldrinNoise73uV(10VFS)S/N>4000Lindane=4820Aldrin=4431ElectronCaptureDetectorStandElectronCaptureDetectorLindaneAldrinNoise73uV(10VFS)V=1.6uL@30pg/uLMassLindane=48pgLindaneA=6122928(0.1uV*s)MDL=3N/S

S=Area(uV*s)/mass

MDL=219(uV)*48(pg)/612292.8(uV*s)=0.0172pg/s=17fgLindane/sMDLCalculation(Lindane)ElectronCaptureDetectorLindaElectronCaptureDetectorMultiplesimultaneousdetectionFID,NPDorFPD

stackedonECDElectronCaptureDetectorMultiAirColumneffluent+Hydrogen/MakeupHeatedsource(Rbceramicmatrix)CollectingelectrodeNitrogenPhosphorousDetector

SpecificresponsevsNandP

organiccompoundsIonization-typedetectorMassdetectorDestructiveRbceramicbeadasthermionic

ionizationsourceAirColumneffluent+Hydrogen/Sampledecomposition?Electronegativeproducts(e.g.NO2,CN,PO2)2+Hotsource?NegativeionsElectronegativespeciesNPD:detectionmechanismTID-2(BlackSource)SampledecompositiSample?Electronegativedecompositionproducts+Hotsource?NegativeionsElectronegativespecies2ENSmode:detectionmechanismTID-1(WhiteSource)Sample?ElectronegativedecoNPDmode:newglassbeadCanreplaceTID-2sourceHigherresponsefor

Phosphorouscompounds

(…buttailingpeakscanbe

observed)Loweroperatingcurrent:

extendedlifetimeSameflowratessettingas

TID-2Blos-Source(GlassBead)NPDmode:newglassbeadCanrThethermionicsourceelementisaconsumablecomponentthatmustbereplacedperiodicallyEasilyinterchangeablethermionicsourcesThermionicsourcelifetimeisstrictlydependentontheoperativeconditions.

NitrogenPhosphorousDetectorThethermionicsourceelementTechnicalSpecificationsOperatingtemperaturelimit 450°CLinearrange betterthan104

Minimumdetectableamount 5x10-2pgN/s 2x10-2pgP/sSelectivity N/C=105:1 P/C=2x105:1Inputrange 0to10-6AInputattenuation 4steps(100-101-

102-

103)Heatingcurrentsetting1.00to3.50Ain0.01stepPolarizationvoltagesetting1.0to9.9Vin0.1stepNitrogenPhosphorousDetectorTechnicalSpecificationsOperNitrogenPhosphorousDetectorStandardOperatingProcedureSOPAzobenzeneMethylparathionAreaCounts

>1500000(Azobenzene)

>3000000(Methylparathion)Azobenzene=1598004Methylparathion=4688635NitrogenPhosphorousDetectorSNitrogenPhosphorousDetectorAzobenzeneMethylparathionMDLCalculation(Azobenzene)V=1.6uL@1ng/uLMassAzobenzene=1.6ng

%N=15.3%

MassN=0.244ngazobenzeneA=1598004(0.1uV*s)MDL=3N/S

S=Area(uV*s)/mass

MDL=54(uV)*0.244(ngN)/159800.4(uV*s)=8.24E-5ngN/s=8.2E-2pgN/sNoise18uVNitrogenPhosphorousDetectorAFlamePhotometricDetectorspecificresponsevsSorP

compoundsdestructivelight-emissiondetectionmassdetectorsingle-flamedesigndualparallelconfigurationFlamePhotometricDetectorspFlamePhotometricDetectorPrincipleofoperationSulphurcompoundsH2S+HHS+H2HS+HS+H2S+SS2*S+S+MS2*S2*S2+hQuadraticresponseforsulfurcompounds!PhosphorouscompoundsPO+H+MHPO*+MPO+OH+H2HPO*+H2OHPO*HPO+hFlamePhotometricDetectorPrinFlamePhotometricDetectorChemiluminescentemissionspectraofsulfurandphosphorouscompoundsinhydrogen-richflameEmissionsignalWavelength(nm)Wavelength(nm)Sulfur(S2*)Phosphorous(HPO*)FlamePhotometricDetectorChemFlamePhotometricDetectorTheemissionofexcitedmoleculesismeasuredagainst

someflamebackgroundbymeansofnarrowbandpass

interferenceopticalfilters:S394nmP526nmSn610nmFlamePhotometricDetectorThFlamePhotometricDetectorNon-linearresponseinsulfur-selectivedetection

Intensityofthesulfuremission:

I[S]nlog[S]1/nlogI

theexponentialfactornistheoreticallyequalto2itisdependentupontheFPDoperatingconditionsitisstronglycompounddependentitisexperimentallydeterminedFlamePhotometricDetectorNon-FlamePhotometricDetectorQuenchingeffectinsulfur-selectivedetection

collisionalquenchingofS2*byCO2,CH4,andother

combustionproductsreducesthesulfurresponsehydrocarbonsareparticularlyeffectiveinquenchingthe

sulfurresponseincaseofcoelutionathighconcentrations,quenchingeffectmaybe

observed,leadingtoacurvatureofthecalibrationcurveFlamePhotometricDetectorQuenFlamePhotometricDetectorTheoptimumairflowrateshouldbeexperimentallydeterminedafter

correctsettingofthehydrogenflowrateVariationsintheair/hydrogenratioleadtodeviationsfromthe

sulfurquadraticresponseWhenoperatinginphosphorousmode,variationsintheair/hydrogen

ratiocanstronglyaffecttheresponseforcertainphosphorous

compoundswhiletiophosphatesareunaffectedThepositionofthecolumnendisespeciallycritical,sincemost

compoundscontainingsulfurandphosphorousareveryactiveThephotomultipliertubenoiseincreaseswithincreasingdetector

temperatureByincreasingtheH2/airratio,thenegativeresponseofHCdecreaseandalsotheScompoundstailingdecreasesPracticalhintsFlamePhotometricDetectorTFlamePhotometricDetectorMaintainingandtroubleshooting

ifahighnoiseandstandingcurrentisobserved,itcanbedueto:

-columnbleeding-opticalsystemnotlight-tight-toohightemperaturenearthephotomultipliertubeiflowsensitivityisobserved,itcanbedueto: -hydrogenflowratetoolow

-airflowratetoohigh -reducedopticalclarityonopticalwindowstopreventdamagingthephotomultipliertube,avoidanyexposuretolight,

evenforshortperiod,whenpoweredon.FlamePhotometricDetectorMainFlamePhotometricDetectorTechnicalSpecificationsFPDtemperaturelimit 350°CSulfurfilter 394nmPhosphorousfilter 526nmDetectionlimit Sulfur5x10-12gS/s(Parathion) Phosphorous1x10-13gP/s(Parathion)Selectivity S/hydrocarbon105 P/hydrocarbon106Linearrange 103forSulfurafterlinearization 104forPhosphorousPhotomultiplierTubeVoltageselectableto800V(low)

and900V(high)FlamePhotometricDetectorTechFlamePhotometricDetectorStandardOperatingProcedureSOP(Sfilter394nm)S/N>40S/N=73MethylparathionNoise213uVFlamePhotometricDetectorStanFlamePhotometricDetectorMethylparathionNoise213uVMDLCalculation(Sfilter394nm)V=1.6uL@1ng/uLMassMethylparathion=1.6ng

%S=12.1%

MassS=0.194ngMethylparathionA=257001(0.1uV*s)MDL=(3N/S)?

S=(Area(uV*s)/mass)*(PW?/mass)S=

25700(uV*s)/194(pgS)*1.34(s)/194(pgS)

=0.91uV/(pgS/s)2

MDL=(639(uV)/0.91)?=26.5pgS/sFlamePhotometricDetectorMethGeneralOverviewofDetectorSystemsDanielaCavagninoGeneralOverviewofDetectorSDetectorsclassificationUniversalTheyrespondtoeverythingelutingfromthecolumnTCDPDD(FID)SelectiveTheymaybeelementselective,structure/functionalgroupselectiveorselectivetootherpropertiesFID(verybroad

selectivity)ECDPIDPDDSpecificTheyaresoselectivetodistinguishparticularstructuresorelementsNPDFPDDetectorsclassificationUniverConcentrationvsMassdependentresponseCommonconc.dependent:TCDPIDPDDECDCommonmassdependent:FIDNPDFPDNon-DestructivevsDestructiveCommonnon-destructive:TCDPIDPDDECDCommondestructive:FIDNPDFPDDetectorsclassificationConcentrationvsMassdependenDetectorResponseCharacteristicsSensitivityDetectorefficiencytoconvertthesampleinanelectricalsignalNoiseShortterm:highfrequencybaselinefluctuationLongterm:lowfrequencybaselineperturbationDynamicRangeRangeofsampleconcentrationforwhichthedetectorcanprovideadetectablesignalvariationwithanalyteamountSelectivityTheratioofthedetectorsensitivitiesofagivencompoundoverapotentiallyinterferingcompoundMinimumDetectabilityAmountofsampleinwhichthepeakheightis3timesthenoiseheight(S/N=3)DetectorResponseCharacteristDetectorResponseCharacteristics

SensitivityandMinimumDetectabilityFIDsensitivity:S===coulomb/g=FPDsensitivityforsulfur:S=*=uV/(gS/s)2MDA===g/secRF(ResponseFactor)=MDA==gS/secpeakareasampleweightA*secgpeakareaSamountPW?Samount3NSA*gA*secpeakareaamount3NSpeakheightmassraten-1?DetectorResponseCharacterist

DynamicandLinearRangeDynamicrange:overwhich

anincrementalchangeinthe

amountofcompoundsinthe

detectorvolumeproducesa

measurableincremental

changeinthedetectorsignalLinearrange:overwhich

theresponsedeviationisless

than5%DetectorResponseCharacteristicsDynamicandLinearRangeDyFlameIonizationDetectorUniversalresponseIonizationdetectionMassdetectorDestructiveFlameIonizationDetectorUnivFlameIonizationDetectorHydrogenismixedwithgasstreamatbottomofjetandairoroxygenissuppliedaxiallyaroundthejetHydrogenflameburnsatthetip,whichalsofunctionsascathodeanditiselectricallyinsulatedfromthebodyCollectorelectrodeisabovetheburnertipFlameIonizationDetectorHydroFlameIonizationDetectorPrincipleofoperationCombustionof

organiccompoundsina

oxidizingflameCH+OCHO++e-Electricfieldbetween

thejetandthecollector

electrodeVoltage-300VCollectionofthe

ionsgeneratedinto

theflameCurrentpAAgoodcombustionstepistheprevailingfactortogetthebestperformancesFlameIonizationDetectorPrincFlameIonizationDetectorItrespondstoallorganiccompoundsexceptforformicacidResponseisgreatestwithhydrocarbonsanddecreaseswithsubstitutionSensitivityhighduetolownoiselevelNoresponsetowater,permanentgases,andinorganiccompoundssimplifiestheresolutionofcomponentsinanalysisofaqueousextractsandinairpollutionstudiesSuitableforfastandultrafastGCapplicationsFlameIonizationDetectorItrFlameIonizationDetectorTechnicalSpecifications

Operatingtemperaturelimit 450°CwithceramicjetLinearrange betterthan106

Minimumdetectableamount 3x10-12gC/sInputrange 0to10-6AInputattenuation 4steps(100-101-

102-

103)Electrodepolarizationvoltage -300VTimeconstant 6ms@63.2%Acquisitionrate upto300HzFlameIonizationDetectorTechnFlameIonizationDetectorStandardOperatingProcedure(SOP)C12C14C16AreaCounts>4000000C12=6877493C14=6790762C16=6988181FlameIonizationDetectorStandFlameIonizationDetectorMDLCalculation(C12)C12C14C16V=1.6uL@20ng/uLMassC12=32ng%C=84.7%MassC=27.1ngC12A=6877493(0.1uV*s)MDL=3N/S

S=Area(uV*s)/mass

MDL=48(uV)*27.1(ngC)/687749.3(uV*s)=0.00189ngC/s=1.89pgC/sNoise16uVFlameIonizationDetectorMDLCElectronCaptureDetectorSelectiveresponseNon-destructiveIonizationdetectorprincipleConcentration-dependentdetectorRadioactivesource63Ni(10mCiactivity)Displacedcoaxial-cylindergeometryElectronCaptureDetectorSelecPrinciplesofdetectionElectronCaptureDetector---e-e-+++-MMMABAB_+*+N2 +N2++e-*+Ar +Ar++e-+Ar*Ar*+CH4 Ar+e-+CH4+dissociative-capturemechanismAB+e- A·+B-nondissociativemechanismAB+e- AB-sidereactionsC+e- C-N2++e- neutralsAB-+N2+ neutralsPrinciplesofdetectionElectrElectronCaptureDetectorPulsedvoltage[e-]V500TTime(s)w=0.11sPULSEvoltageDCvoltageElectronCaptureDetectorPulse

ElectronCaptureDetectorConstantcurrentmethodI=Ke-]f+-Iff=constI=constElectronCaptureDetectorConsConstantcurrentmethodModulationofPulseFrequencyioncurrent=electronsconcentrationxpulsefrequencywithnosample freq.=f°withelectronegativesample freq.=fssignaloutput=fs-f°=sampleconcentrationElectronCaptureDetectorConstantcurrentmethodModulatElectronCaptureDetectorRadioactivesource: Nickel63–370MBq(10mCi)Cellvolume 450LOperatingtemperaturelimit: 400°CMinimumdetectableamount: 10fgoflindaneLineardynamicrange: 104(argon/methane)

103(nitrogen)Operationmode: constantcurrentpulse-modulatedmodeReferencecurrent: 0to3nA(0.1nAsteps)Pulseamplitude: 5to50Vneg.Pulsewidth: 0.1s(argon/methane),

0.5s,1s(nitrogen)TechnicalSpecificationsElectronCaptureDetectorRadioElectronCaptureDetectorMolecularfeaturesgoverningtheresponseofECDLowresponseforalcohols,amines,phenols,aromaticsandvinyl

typefluorinatedhydrocarbonsHighresponseforhalocarboncompounds,nitroaromatics,and

conjugatedcompoundscontainingtwogroupswhichindividually

arenotstronglyelectronattractingbutbecomesowhen

connectedbyspecificbridgesResponsetowardsthehalogensdecreasesintheorderI>Br>Cl>FElectronCaptureDetectorMolecElectronCaptureDetectorMolecularfeaturesgoverningtheresponseofECDMultiplesubstitutionwithsimpleelectronattractinggroupsor

atomsmayincreasethemolecularabsorptionbyanamountmuch

greaterthanexpectedofasimpleadditiveeffectTheabsorptionconferredbyasimpleelectrophoricgroupisalso

sensitivetothepositioninthemoleculeSomeinorganiccompoundsareelectronabsorbers,ascarbon

disulfide,ozoneandtheoxidesofnitrogenElectronCaptureDetectorMolecElectronCaptureDetectorRelativesensitivityEthaneBenzene 1ButanolAcetoneChlorobutane 1-102Chlorobenzene1,2-dichlorobenzeneAntracene 102-104ChloroformNitrobenzene 104-105CarbontetrachlorideDinitrophenolDiethyloxalate 105-106DihydropyridineInfluenceofdetectortemperatureDetectionlimit(x10-9g)CCl4 0.010.010.01CHCl31.00.10.05CH2Cl21000408CH2ClCH2Cl1000201

80°C227°C350°CElectronCaptureDetectorRelatElectronCaptureDetectorRelativeresponseofhalocarbonsCF3CF2CF3 1.0CF3Cl 3.3CF2=CFCl 100CF3CF2Cl 170CF2=CCl2 670CF2Cl2 3x104CHCl3 3.3x104CHCl=CCl2 6.7x104CF3Br 8.7x104CF2ClCFCl2 1.6x105CF3CHClBr 4.0x105CF3CF2CF2I 6.0x105CF2BrCF2Br 7.7x105CFCl3 1.2x106ElectronCaptureDetectorRelatg-LINDANEMDA=10fgwithS/N=3ALDRIN(15pg)HEPTACHLOR(10pg)g-LINDANE(10pg)x2x64ECDperformanceMinimumDetectableAmountg-LINDANEMDA=10fgwithSBestconditionsforECDsensitivity

ECDsensitivityisaffectedbythefollowingfactors:

Referencecurrent

Thehigheristhereferencecurrent,thegreateristhesignalresponsebut

alsothebaselinenoise.TheS/Nrationeedstobe