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