3 MS Intr1 Dr Mufeed
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Transcript of 3 MS Intr1 Dr Mufeed
Introduction to TurboMassGC/MSDr. Mufeed Batarseh
Training course 21-24 Jan 2007
Prince Faisal center for Dead sea, Environmental and Energy Research
GC/MS Introduction 2
Why GC/MS?
Universal and specificSensitivePositive identification with standard or library spectrumInterference-free quantitationIsotopically labeled internal standards
GC/MS Introduction 3
What is GC/MS ?
Composite instrument made up of GC and MS
GC + MS GC/MS• GC is superior in separating of multi-components.
• GC is not good at identifying peak components.
• MS allows identification from mass spectrum.
• SIM method of GC/MS allows accurate quantitation.
GC/MS Introduction 4
Capabilities of GC/MS
Combines separation and identification techniquesProvides both quantitative and qualitative information about sampleOffers the best solution to many analytical problemsInterference-free quantitation
GC/MS Introduction 5
Sensitivity and Selectivity
Full Scan- Detection Limits of 1 - 10 picograms- Identification of unknowns by reference library - Confirmation by retention time and spectra
Selected Ion Mode- Detection Limits of 10 - 100 femtograms- Identification by retention time- Confirmation by Ion ratios
Selectivity- Compound (vs. functionality like ECD or NPD)
GC/MS Introduction 6
Universal and SpecificInterference-Free Quantification
Universal Specific
GC/MS Introduction 7
Universal and Specific
GC/MS Introduction 8
The GC/MS Interface
Inlet Inlet SystemSystem
GCGC
IonIonsourcesource
MassMassAnalyzerAnalyzer DetectorDetector
VacuumVacuumGaugesGauges
Vacuum Manifold
High VacuumHigh VacuumPumpPump
BackingBackingPumpPump
Data SystemData System MSMSElectronicsElectronics
TransferTransferlineline
GC/MS Introduction 9
Jet Separator
VacuumFromGC
ToMS
GC/MS Introduction 10
Direct Capillary Interface
Advantages- Simple- Low cost- Minimal
reactivitydead volumeselectivity
Disadvantages- Limited flow rate- Limits column ID range
GC/MS Introduction 11
Why is an Ion Source Needed?
Charged particles (ions) can be easily manipulated with electrical and magnetic fields- focusing- diverting- filtering- detecting
Neutral particles (molecules) are much more difficult to manipulate
GC/MS Introduction 12
Sample Ionization for GC
Electron Ionization (EI)- High energy - 70 eV- Positive Ions- Fragmentation - Structural information
Chemical Ionization (CI)- Low energy- Positive and Negative Ions- Ion-molecule reactions with Reagent Gas- Methane, Isobutane, Ammonia typical
GC/MS Introduction 13
Sample Ionization
GC/MS Introduction 14
Electron Ionization Source
GC/MS Introduction 15
Electron Ionization Reactions
+ e-molecule molecule+ . + 2e-
Fragmentationmolecule
+ mole
++ cule
ion radical
. .
mole+
mo+
+ le
neutral molecule
GC/MS Introduction 16
Advantages of Electron Ionization
Simple constructionHigh ionization efficiency (10-5)Highly characterized fragmentation patterns“Fingerprints”Existing computer-searchable libraries of EI spectraLimited secondary reactions due to collisions
GC/MS Introduction 17
Disadvantages of Electron Ionization
Sample must be in gaseous stateCan cause excessive fragmentationSome compounds do not yield molecular ionSpectra may not distinguish between isomersSome spectra are very complicated
GC/MS Introduction 18
Positive Chemical Ionization Reactions
R + e- R+ + 2e-
R+ + RH RH+ + RRH+ + M MH+ + R
R = reagentM = sample moleculee- = electron
= radical electronH = hydrogen
GC/MS Introduction 19
Reagent Gas Ions
Reagent Gas Molecular Ion Reagent Ion
CH4 CH4+. CH5
+
H2 H2+. H3
+
C4H10 C4H3+. C4H11
+
NH3 NH3+. NH4
+
CH3OH CH3OH+. CH3OH2+
NO NO+. NO+
GC/MS Introduction 20
Advantages of Chemical Ionization
Minimal fragmentationMW information, even when EI may notReagent gases can be compound selective- Selectivity by proton or electron affinity- Isomer selectivity possible- Double-bond location- ECD selectivity possible
ECD-like sensitivity possibleLower background spectra
GC/MS Introduction 21
Disadvantages of Chemical Ionization
Less fragmentation than EISpectrum not as informativeResults depend on:- reagent gas type, pressure- temperature and reaction time- analyte
Spectrum may not be reproducible enough for library search No commercially available computer-searchable spectral librariesRequires more frequent ion source maintenance
GC/MS Introduction 22
The Mass Analyzer
Inlet Inlet SystemSystem
GCGC
IonIonsourcesource
MassMassAnalyzerAnalyzer DetectorDetector
VacuumVacuumGaugesGauges
Vacuum Manifold
High VacuumHigh VacuumPumpPump
BackingBackingPumpPump
Data SystemData System MSMSElectronicsElectronics
TransferTransferlineline
GC/MS Introduction 23
Types Of Mass Analyzers
Magnetic Sector- High resolution- High sensitivity- High cost
Time-of-Flight (TOF)- High speed
100 - 1000 spectra/second- High sensitivity- Wide mass range- High cost
GC/MS Introduction 24
Types of Mass Analyzers (continued)
Ion Trap- Complex Sample Matrix may cause problems- Self Induced CI- MS/MS
Quadrupole- Rapid Scanning- Easily Interfaced- High Sensitivity- Best GC Detector EVER MADE
GC/MS Introduction 25
Advantages of Quadrupole MassSpectrometry
High SensitivitySimplicity of OperationImmunity to coeluting peaksRapid ScanningSingle and Multiple Ion ScanningEasily Interfaced
GC/MS Introduction 26
Quadrupole
Filament
Electron Reflector
ElectronMultiplier
GC Column
Quadrupole Mass Filter
Ionizer
Lens 2Lens 1
Entrance Lens
GC/MS Introduction 27
Quadrupole Mass Analyzer
m2m2 m4m4
m3m3m1m1
++ ++ ++
+V+Vrfrf onlyonly
++++ ++
( +V( +Vdcdc + V+ Vrfrf cos wt)cos wt)
m4m4m2m2 m3m3m1m1
GC/MS Introduction 28
The Detector
Inlet Inlet SystemSystem
GCGC
IonIonsourcesource
MassMassAnalyzerAnalyzer DetectorDetector
VacuumVacuumGaugesGauges
Vacuum Manifold
High VacuumHigh VacuumPumpPump
BackingBackingPumpPump
Data SystemData System MSMSElectronicsElectronics
TransferTransferlineline
GC/MS Introduction 29
Detectors
Electron Multiplier- Continuous Dynode- Discrete Dynode- Electron Multiplier Disadvantages
Lifetime limited by ion dosageContaminationHV discharge
Photomultiplier- Long life (10 years)- Immune to contamination
GC/MS Introduction 30
Continuous Dynode Electron Multiplier
EM Gain with Time
103
104
105
106
107
Gai
n
2 6 10 14 18Time (months)
-300
00
EM
vol
tage
ion
GC/MS Introduction 31
Photomultiplier
Photocathode
Electron optics
Focusing Electrode First dynode
Electronmultiplier
Anode
MountingBase
GC/MS Introduction 32
Photomultiplier Detection System Conversions
Ions
Conversion Dynode
Electrons
Phosphor
Photons
Photomultiplier
Electron Current
GC/MS Introduction 33
Photomultiplier
PhotoelectronDynodes
Secondaryelectrons
Anode
current-to-voltageamplifierHigh voltage (-)
200 - 2000V
Photoemissivecathode
Radiationhν
GC/MS Introduction 34
Vacuum System
Inlet Inlet SystemSystem
GCGC
IonIonsourcesource
MassMassAnalyzerAnalyzer DetectorDetector
VacuumVacuumGaugesGauges
Vacuum Manifold
High VacuumHigh VacuumPumpPump
BackingBackingPumpPump
Data SystemData System MSMSElectronicsElectronics
TransferTransferlineline
GC/MS Introduction 35
Turbomolecular Pump
toroughing
pump
Fixed blade
Rotating blade
Motor
GC/MS Introduction 36
GC/MS Summary
Universal and specificSensitivePositive identification with standard or library spectrumInterference-free quantitation
GC/MS Introduction 37
TurboMass Physical Components
Inlet Inlet SystemSystem
AutoSystemAutoSystem
IonIonsourcesource
MassMassAnalyzerAnalyzer DetectorDetector
VacuumVacuumGaugesGauges
Vacuum Manifold
High VacuumHigh VacuumPumpPump
BackingBackingPumpPump
Data SystemData System MSMSElectronicsElectronics
TransferTransferlineline
GC/MS Introduction 38
Vacuum Pumps
High Vacuum Pump - 250 L/sec Turbomolecular
Backing Pump- 3.0 m3/hr mechanical pump
GC/MS Introduction 39
250 L/sec Turbomolecular Pump
Software controlled pump downWater cooling optionHardware controlled vent valve- vents when pump slows to
50% full speedMaintenance free
GC/MS Introduction 40
TurboMass Ion Optics
Filament
Magnet
PreQuads
AnalyticalQuadrupole
Photo-multiplier
PhosphorScreen
ConversionDynode
+
Magnet
Collector
Lens 2
Repeller
Lens 1
GC/MS Introduction 41
Ion Optics
OuterIon Source
PrefilterQuadrupole
ConversionDynode PhosphorGC
Column
PMT
RF AmplifierReference & CIGas Inlets
GC/MS Introduction 42
Thank you