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Mass Spectrometry

Ionization Techniques

and

Mass Analyzers

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Mass Spectrometer

All Instruments Have:

1. Sample Inlet

2. Ion Source

3. Mass Analyzer

4. Detector

5. Data System

http://www.asms.org

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Ionization Techniques

Gas-Phase Methods Electron Impact (EI)

Chemical Ionization (CI)

Desorption Methods Matrix-Assisted Laser Desorption Ionization (MALDI)

Fast Atom Bombardment (FAB)

Spray Methods Electrospray (ESI)

Atmospheric Pressure Chemical Ionization (APCI)

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Electron Impact

http://www.noble.org/PlantBio/MS/ion_tech_main.html

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Electron Impact

Advantages

Well-Established

Fragmentation Libraries No Supression

Insoluble Samples

Interface to GC

Non-Polar Samples

Disadvantages

Parent Identification

Need Volatile Sample Need Thermal Stability

No Interface to LC

Low Mass Compounds

(

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Chemical Ionization

http://www.noble.org/PlantBio/MS/ion_tech_main.html

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Chemical Ionization

Advantages

Parent Ion

Interface to GC Insoluble Samples

Disadvantages

No Fragment Library

Need Volatile Sample Need Thermal Stability

Quantitation Difficult

Low Mass Compounds

(

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FAB

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FAB

Advantages

Parent Ion

High Mass Compounds(10,000 amu)

Thermally Labile

Compounds (R.T.)

Disadvantages

No Fragment Library

Solubility in Matrix(MNBA, Glycerol)

Quantitation Difficult

Needs Highly SkilledOperator

Relatively LowSensitivity

(nanomole)

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MALDI

http://www.noble.org/PlantBio/MS/ion_tech_main.html

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MALDI

Advantages

Parent Ion

High Mass Compounds(>100,000 amu)

Thermally Labile

Compounds (R.T.)

Easy to Operate

Disadvantages

No Fragment Library

Wide variety of matrices Quantitation Difficult

(low femtomole)

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ESI

http://www.noble.org/PlantBio/MS/ion_tech_main.html

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ESI

Advantages

Parent Ion

High Mass Compounds(>100,000 amu)

Thermally LabileCompounds (

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APCI

http://www.rzuser.uni-heidelberg.de/~bl5/ency/ency.html

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APCI

Advantages

Parent Ion

Insensitive to Salts Interface to HPLC

Can use Normal Phase

Solvents

Handles High FlowRates

Disadvantages

Need Volatile Sample

Need Thermal Stability

(high femtomole)

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Mass Analyzers

Double Focusing Magnetic Sector

Quadrupole Mass Filter

Quadrupole Ion Trap

Linear Time-of-Flight (TOF)

Reflectron TOF Fourier Transform Ion Cyclotron

Resonance (FT-ICR-MS)

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Double-Focusing Magnetic Sector

http://www.asms.org

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Advantages

Very High Resolution

(60,000)

High Accuracy (

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Quadrupole Mass Filter

http://www.asms.org

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Advantages

Inexpensive

Easily Interfaced toMany Ionization

Methods

Disadvantages

Low Resolution (100ppm)

MS/MS requires

multiple analyzers

Low Mass Range(

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Quadrupole Ion Trap

http://www.asms.org

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Advantages

Inexpensive

Easily Interfaced toMany Ionization

Methods

MS/MS in one analyzer

Disadvantages

Low Resolution (100ppm)

Space Charging

Causes Mass Shifts

Low Mass Range(

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Linear Time-of-Flight (TOF)

http://www.asms.org

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Advantages

Extremely High Mass

Range (>1 MDa)

Fast Scanning

Disadvantages

Low Resolution (4000)

Low Accuracy(>200ppm)

MS/MS not possible

Linear Time-of-Flight (TOF)

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Reflectron Time-of-Flight (TOF)

Courtesy Bruker Datonics BioTOF users Manual

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Advantages

High Resolution

(>20,000 in some

models)

High Accuracy (

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FT-ICR-MS

http://www.asms.org

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Advantages

Extremely High

Resolution (>500,000)

Very Good Accuracy

(