External ionization source improvements for fourier transform ion cyclotron resonance mass spectrometry

2004·4.6 MB·English

by  Zientek, Keith David

EXTERNALIONIZATIONSOURCEIMPROVEMENTSFORFOURIER
TRANSFORMIONCYCLOTRONRESONANCEMASSSPECTROMETRY
By
KEITHDAVIDZIENTEK
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
2004
Thisdissertationisdedicatedtomygrandfather,RodneyLawton.
ACKNOWLEDGMENTS
Firstly,IwouldliketothankSifuDaleHerring. Ihadbeenaspringboarddiver
fromthe5*gradeallthewaythroughcollege. AfterIcametotheUniversityofFlorida,1
foundthelackofasportsteamledmetogrowcomplacent. IdonotthinkIwasever
properlyfocuseduntilIbegantotrainwithSiftiDaleHerring. Martialartshasservedto
keepmehealthy,bothphysicallyandmentally,overthelastfouryears. Ithankhimfor
trainingmeandgivingmesomedisciplinethatIthoughtIalwayshad. Teachingmehow
touseswordswasanunexpectedbutappreciatedbonus.
Secondly,Iwouldliketothanksomeofthepeoplewhohavehelpedmeoutinmy
researchovertheyearswithadviceandassistance. SteveMilesandLarryHartleyofthe
chemistryelectronicsshophaveprovidedexcellentadviceonelectronicsandJoe
ShaloskyandToddProxofthechemistrymachineshophavebeenafountofknowledge
ondesignandconstruction. Theirassistancehasbeenimmeasurableandessentialtothe
completionofthisresearch.
Thirdly,IwouldliketothankthepastandpresentmembersoftheEylerresearch
groupaswellasDr.JohnEyler. GroupmemberssuchasStanleyStevens,Jr.andSusan
Abbatiellohaveprovidedmuchassistanceandwereinvaluabletothecompletionofthis
research. Dr.JohnEylerhasbeenasourceofenthusiasmandknowledgetomeandIam
forevergratefultohaveworkedforhim. Iknewthatanyproblemcouldbesolvedwith
hismentoringandthediscussionswehadprovedtobeessentialtomyunderstandingof
iii
anytopicthatIhappenedtohavequestionsaboutonthatparticularday. This
dissertationwouldnothavebeenpossiblewithouthisguidance.
1wouldliketothankmyfamily,especiallymyfather,whohasprovidedboth
encouragementandcriticismatalltherighttimes. Hisenthusiasmforscienceand
learningwasalmostinspirationalattimesandwasthemajorcontributiontothegenesis
ofmysciencecareer. MyparentswerethefoundationofmyentireacademiccareerandI
oweeverythingtothem. IwouldalsoliketothankEllenSternforallofherlove,
devotion,andfaithinme. Withouthernoneofthiswouldhavebeenpossible. Her
supportandguidancehavebeencrucialtomysuccess.
Finally,1wouldthankmylategrandfather,RodneyLawton. Itwashisoptimism
andenthusiasmthatservedasmotivationformeduringtoughtimes. Evenwhen1had
doubts,healwaysbelievedthatIwouldearnmydoctorate. Forhisunwaveringsupport,I
dedicatethisdissertationtomygrandfatherinhopesofhonoringhismemory.
IV
657
TABLEOFCONTENTS
page
ACKNOWLEDGEMENTS
ii
LISTOFTABLES vi
LISTOFFIGURES vii
ABSTRACT xi
CHAPTER
1 FTICRMASSSPECTROMETRY 1
Introduction 1
IonMotioninaMagneticField 3
IonTrapping 6
Excitation(SingleFrequency) 8
Detection(SingleFrequency) H
FourierTransform 1
Excitation(Broadband) 1
FTICRComparedtootherMassAnalyzers 1
AdvantagestoIncreasedMagneticFieldStrength 18
BroadbandExcitationSchemes 19
FTICRPulseSequence 20
ComponentsofanFTICRMassSpectrometer 20
Conclusions 23
2 MASSSEEECTIONINMULTIPOEEIONGUIDES 25
Introduction 25
EquationsofMotioninaQuadrupole 30
StabilityDiagramsforMultipoles 35
3 GLOWDISCHARGEFTICRMASSSPECTROMETRY 40
V
1
Introduction 40
TheGlowDischargeProcess 41
GlowDisehargeMassSpectrometry 45
Interferences 45
MassAnalyzers 47
GD-FTICRMassSpeetrometry 48
Experimental 52
Results 54
Conclusions 63
4 ELECTROSPRAYIONIZATIONFTICRMASSSPECTROMETRY 64
Introduction 64
Experimental 66
Results 69
Conclusions 76
5 ATMOSPHERICPRESSUREIONIZATION 77
Introduction 77
AtmosphericPressureChemiealIonization 77
AtmospheriePressurePhotoionization 79
Instrumentation 8
EstrogensandEstrogenDerivatives 83
Experimental 85
Results 87
Conclusions 90
6 CONCLUSIONSANDFUTURESTUDIES 91
REFERENCELIST 95
BIOGRAPHICALSKETCH 100
VI
LISTOFTABLES
Table Page
2.1 Maximaandminimaforavarietyofmultipoleswithordern 38
3.1 Ionizationeventsinglowdischargeplasma 43
3.2 Massresolvingpowersrequiredtoseparateseveralatomicions
andpotentialinterferences 46
3.3 Advantagesanddisadvantagesofseveraltypesofmassanalyzersfor
elementalanalysis 49
3.4 ThecertifiedcompositionofNISTSUM1104,free-cuttingbrasspinsample 62
4.1 MajorIonsfoundinPNG2422A 75
5.1 Summaryofsomepossiblereactionsinacoronadischarge 79
5.2 ReactionsfoundintheAPPIionizationsource 80
5.3 Gasphaseionizationenergiesofsomecommongasesandsolvents 81
5.4 ReactionsinvolvingdopantintheAPPIionizationsource 82
vii
5
LISTOFFIGURES
Figure
page
I.I TheLorentzforceactsuponchargedparticlesinthepresenceofan
externalmagneticfield,Bo 4
1.2 Ionmotionwhichisradiallyconfinedinthexandydirectionsbyan
externalmagneticfield,B,actingalongthezaxis 6
1.3 Apositivevoltageappliedtothetrappingplateswillconfineions
axiallyintheICRanalyzercell 7
1.4 Ionsareinitiallyconfinednearthecenterofthecellinapartially
incoherentpacket. UpontheapplicationofanRFpulsetothe
excitationelectrodes,theionsareacceleratedtoacoherentpacket
inalargerorbit 10
1.5 Themovementoftheexcitedionadjacenttothedetectplatesinduces
asinusoidalcurrentintheplates. Thefrequencyofthecurrentis
equivalenttothecyclotronfrequenciesoftheions 12
1.6 Astheradiusoftheionsdecreasesduetocollisionsbetween
backgroundneutralsandothermolecules,theinducedsignal
alsodecreases 13
1.7 ThemathematicalFouriertransformconvertsatimedomainsignal
intoafrequencydomainspectrum. Masscalibrationgivesthem/q
massspectrum 1
1.8 AtypicalFTICRmassspectrometeroutfittedwithanElectron
Ionization(El)source 22
2.1 Behaviorofapositiveioncenteredbetweentwoelectrodes. A
sinusoidalwaveformisappliedtoElectrodes1and2. Thewaveform
appliedtoElectrode2is180degreesoutofphasefromthewaveform
appliedtoElectrode1 26
viii
2.2 Cross-sectionalviewofaquadrupolararrangementofelectrodes 28
2.3 Equipotentialfieldlinesinaquadrupolararrangementofelectrodes 29
2.4 Stableandunstableiontrajectoriesinaquadrupoleionguide 33
2.5 Theoreticalstabilitydiagramforaquadrupoleionguide 34
2.6 Calculatedstabilitydiagramforaquadrupoleionguide 35
2.7 Theoreticalstabilitydiagramforahexapoleionguide. Uindicates
unstableregions,PSindicatespartiallystable,andSindicatesregions
ofstability 36
2.8 Theoreticalstabilitydiagramforaoctopoleionguide. Uindicates
unstableregions, PSindicatespartiallystable,andSindicatesregionsof
stability 37
3.1 FTCRmassspectrometerusedforGDexperiments 52
3.2 SchematicofthecoaxialcathodetypeGDsourceusedintheexperiments 53
3.3 Electricalcircuitusedtoprovidepowertotheoctopolerods 56
3.4 GDFTICRmassspectraobtainedfrompinsamplesofTa,In,andFe 57
3.5 GlowdischargeFTICRmassspectraofacoppersampleshowingthe
effectsofpreselectiononlowabundanceions. Therffrequencyapplied
totheoctopolerodsofthetopspectrumwas1.75MHz,forthebottom
spectrumitwas850kHz 58
3.6 Spectraofabrasssample(NIST1104)showingtheeffectsofpreselection
onlowabundanceions. Therffrequencyappliedtotheoctopolerodsfor
thetopspectrumwas1.9MHz,whiletherffrequencyofthebottomspectrum
was660kHz. Anincreaseinsignalintensityforlead(2.77%abundant)
relativetocopper(61.33%abundant)andtin(35.31%abundant)isseen 59
3.7 SpectraoftheNIST1104brasssampleseeninfigure3.5.Tin(0.43%
abundant)canbeseenabovethenoiseinthebottomspectrum. Themass
rangewasexpandedoverthe100-220m/zrangetoshowdetail. Note
thatthetinwasnotobservableinthetopspectrum 60
4.1 InstrumentalschematicofthemodifiedBrukerApex47ewithamodified
Analyticaelectrospraysource 67
IX
4.2 IonopticsinthemodifiedAnalyticaESIsource. Theionoptics
ateitherendofthehexapoleionguideareusedforionaccumulation 68
4.3 ESIFTICRmassspectraofacontaminated6pMAngiotensinIIsolution.
Eachmassrangeshowsthetwomostprominentclustersofpeaksin
theentiremassspectrum. Thesamplewasrunataflowrateof
17.5pL/hr. Thehexapoleoperationalfrequencywas3.4MHzfor
thetopspectrumand1.9MHzforthebottomspectrum 70
4.4 HighmassrangefromthespectrainFigures4.3and4.2. The
hexapoleoperationalfrequencyis3.4MHzinthetopspectrumand
1.9MHzinthebottomspectrum. Nootheroperationalparameters
werechangedbetweentheacquisitionofeachspectrum. Each
spectrumisasumof64scans 72
4.5 ESIFTICRmassspectraofacontaminated6pMAngiotensinII
solution. Eachcolumnconsistsofseveralzoomedinslicesofa
singlespectrum. ThefrequencyoftheappliedRFforeachspectrum
islistedtotheleftofeachrow. TheY-axisscaleisconsistentacross
eachrow,butnotdownthecolumns 72
4.6 S/NcomparisonsintheAngiotensinspectraforavarietyof
hexapoleoperationalfrequencies. Eachspectrumisasumof64
scans 73
4.7 ESIFTICRmassspectraofa10folddilutionofAgilentTunemix.
Eachcolumnconsistsofseveralzoomedinslicesofasinglespectrum.
ThefrequencyoftheappliedRFforeachspectrumislistedtotheleft
ofeachrow. TheY-axisscaleisconsistentacrosseachrow,butnot
downthecolumns 75
5.1 ComparisonofImportantFactorsforAPPI,APCI,andESI 79
5.2 TwopotentialphotoionizationlampgeometriesusedinAPCI 83
5.3 CutawayschematicoftheAPPIionizationsource. Aisthemass
spectrometerinlet. Bisthephotoionizationlamp. Cistheheated
tube,thestripedbarsindicatetheresistiveheatingelement.Dis
theauxiliarygasinlet. Eisthecapillaryinletforsampleintroduction.
Fisthesheathgasinlet. Gisthealuminummountingplatform.
ThegrayareasrepresentMacorpiecesusedforelectricalinsulation 86
5.4 APPImassspectrumofElquinolin100%MeOH 88
X