《QUADRUPOLE ION TRAP MASS SPECTROMETRY》SECOND EDITION
RAYMOND E. MARCH
Trent University, Peterborough, Ontario, Canada
JOHN F. J. TODD
University of Kent, Canterbury, UK
1 A Historical Review of the Early Development of the
Quadrupole Ion Trap 1
1.1. Introduction, 1
1.2. Principles of Operation, 2
1.3. Utilization of the Quadrupole Ion Trap, 6
1.3.1. Early Mass-Selective Modes of Operation, 6
1.3.1.1. Mass-Selective Detection, 6
1.3.1.2. Mass-Selective Storage, 10
1.3.2. Ion Loss Processes, 12
1.3.2.1. Unstable Trajectories, 13
1.3.2.2. Interactions, 13
1.3.2.3. Nonlinear Resonances, 16
1.3.2.4. Self-Emptying, 17
1.4. The Low-Pressure QUISTOR–Quadrupole Combination, 17
1.5. Early Studies of the Theoretical Aspects of Low-Pressure
Ion Trap Operation, 20
1.6. Research Activities with the Quadrupole Ion Trap, 21
1.7. Mass-Selective Axial Ejection, 23
1.8. Conclusion, 25
References, 25
2 Theory of Quadrupole Instruments 34
2.1. Prelude, 35
2.2. Introduction, 35
2.3. Theory of Quadrupolar Devices, 36
2.3.1. The Quadrupole Mass Filter (QMF), 38
2.3.1.1. QMF with Round Rods, 39
2.3.1.2. The Structure of the QMF, 39
2.3.1.3. Quadrupolar Potential, 40
2.3.1.4. The Mathieu Equation, 42
2.3.1.5. Regions of Stability of the QMF, 43
2.3.1.6. Mass Selectivity of the QMF, 47
2.3.2. The Quadrupole Ion Trap (QIT), 50
2.3.2.1. The Structure of the QIT, 50
2.3.2.2. Electrode Surfaces, 52
2.3.2.3. Quadrupolar Potential, 55
2.3.2.4. An Alternative Approach to QIT Theory, 58
2.3.2.5. Regions of Ion Trajectory Stability, 58
2.3.3. Secular Frequencies, 59
2.3.4. Calculations, 64
2.3.4.1. qz and LMCO, 64
2.3.4.2. βz, 65
2.3.4.3. ωz, 65
2.3.4.4. Mass Range, 65
2.3.5. The Complete Solution to the Mathieu Equation, 65
2.3.6. Secular Frequencies, 67
2.4. Conclusions, 67
Appendix, 68
References, 71
3 Dynamics of Ion Trapping 73
3.1. Introduction, 74
3.2. The Pseudopotential Well Model, 74
3.2.1. Specimen Calculation of the Pseudopotential Well
Depth D
z, 79
3.2.2. Some Applications of the Pseudopotential Well Model, 79
3.2.2.1. Estimation of the Effects of Space Charge, 80
3.2.2.2. Ion Kinetic Energies, 88
3.3. Higher Order Field Components and Nonlinear Resonances, 91
3.3.1. Historical Background, 91
3.3.2. Fundamental Aspects of Nonlinear Resonances, 93
3.3.2.1. Multipole Fields, 93
3.3.2.2. Experimental Observations of Effects Arising from
Nonlinear Resonances in the Quadrupole Ion Trap
Mass Spectrometer, 100
3.3.2.3. Nonlinear Field Effects in Quadrupole Mass
Spectrometers and Linear Ion Traps, 104
3.3.2.4. Mass Shifts, 105
3.4. Motion of Trapped Ions, 112
3.4.1. Collision Processes: Collisional Cooling, 113
3.4.2. Collision Processes: Trapping Injected Ions, 115
3.4.3. Resonant Excitation, 117
3.4.3.1. Resonant Excitation: Ion Ejection, 118
3.4.3.2. Resonant Excitation: Collision-Activated
Decomposition, 120
3.4.3.3. Collision Energies, 122
3.4.4. Boundary-Activated Dissociation (BAD), 124
3.4.5. Surface-Induced Dissociation, 125
3.5. Conclusion, 125
References, 125
4 Simulation of Ion Trajectories in the Quadrupole Ion Trap 133
4.1. Introduction, 134
4.2. Recent Applications of Simulations, 136
4.3. Theoretical Background, 136
4.3.1. Numerical Integration of the Mathieu Equation, 137
4.3.2. Calculation of Electrostatic Fields, 138
4.3.2.1. Direct Method, 139
4.3.2.2. Matrix Field Interpolation, 139
4.3.3. Computer Simulation Programs, 141
4.3.3.1. ITSIM, 141
4.3.3.2. ISIS, 141
4.3.3.3. SIMION, 141
4.3.3.4. Dialogue and Operating Platform, 142
4.3.3.5. Electrode Design, 143
4.3.3.6. Scan Functions and User Programs, 145
4.3.3.7. Ion Definition, 146
4.3.3.8. Calculation of an Ion Trajectory, 148
4.3.3.9. Data Collection and Display, 149
4.3.3.10. Collision Models, 150
4.3.4. Comparison of Simulators, 151
4.3.4.1. Single-Ion Trajectories in a Collision-Free System, 152
4.3.4.2. Collisional Cooling, 155
4.3.4.3. Ion Injection, 156
4.4. Conclusions, 158
References, 159
5 Linear Quadrupole Ion Trap Mass Spectrometer 161
5.1. Introduction, 162
5.1.1. History, 163
5.1.1.1. Mass Discrimination, 163
5.1.1.2. Variable Retarding Field, 163
5.1.1.3. Spectroscopic Studies, 164
5.1.1.4. Resonant Ejection, 164
5.2. Linear Ion Trap, 164
5.2.1. Thermo Finnigan Linear Ion Trap, 164
5.2.1.1. Advantages of a Linear Ion Trap, 165
5.2.1.2. Description of the Thermo Finnigan Linear Ion
Trap, 165
5.2.2. MDS SCIEX Linear Ion Trap, 166
5.2.2.1. Description of the MDS SCIEX Linear Ion Trap, 166
5.2.2.2. Ion Trapping in Collision Cell Qc, 167
5.2.2.3. Mass-Selective Axial Ion Ejection, 168
5.2.2.4. Ion Accumulation in Q0, 168
5.2.2.5. CID by Variation in Precursor Ion Axial
Kinetic Energy, 169
5.2.2.6. Ion Trapping in RF-Only Quadrupole Mass
Filter Q2, 169
5.2.3. Ion Confinement Theory, 169
5.2.4. Ion Trap Capacities, 170
5.2.5. Characteristics of Linear Ion Trap Operation, 171
5.2.5.1. Trapping Efficiency, 171
5.2.5.2. Mass Discrimination, 172
5.2.5.3. Ion Isolation, 172
5.2.5.4. Ion Activation, 172
5.2.5.5. Tandem Mass Spectrometry, 172
5.2.5.6. Spectral Space Charge Limit, 172
5.2.5.7. Ion Ejection, 172
5.2.5.8. Enhanced Mass Resolution, 173
5.2.5.9. Sensitivity, 173
5.2.6. Low-Pressure Linear Ion Trap, Q2, 173
5.3. Rectilinear Ion Trap, 175
5.3.1. RIT Structure, 176
5.3.2. Optimization of the RIT Geometry, 176
5.3.3. Stability Diagram, 177
5.3.4. RIT Performance, 179
5.4. Stacked-Ring Set, 179
5.4.1. Electrostatic Ion Guide, 181
5.4.2. Ion Tunnel, 181
5.4.2.1. Transmission Efficiency, 181
5.4.2.2. Charge State Discrimination, 182
5.5. Conclusions, 184
Appendix, 185
References, 185
6 Cylindrical Ion Trap Mass Spectrometer 188
6.1. Introduction, 189
6.2. Initial Studies of a Cylindrical Ion Trap, 189
6.2.1. Operation of a CIT, 189
6.2.2. Further Development of the CIT, 191
6.2.3. Miniature Ion-Trapping Devices, 191
6.2.3.1. Stored-Ion Spectroscopy, 191
6.2.3.2. Readily Machined Ion Traps, 191
6.3. Miniature Cylindrical Ion Traps (Mini-CITs), 192
6.3.1. Driving Force, 193
6.3.2. Miniaturization, 193
6.3.3. Portable Miniature CIT, 194
6.3.3.1. Vacuum System, 195
6.3.3.2. Ionization Source, 195
6.3.3.3. Detector System, 195
6.3.3.4. Waveform Generation, 196
6.3.3.5. Control Software, 196
6.3.4. Mini-CIT System Performance, 198
6.3.4.1. Mass Calibration, 198
6.3.4.2. Tandem Mass Spectrometry, 199
6.3.4.3. Limit of Detection and Mass
Resolution, 201
6.4. Membrane Introduction Mass Spectrometry, 201
6.5. Miniature Cylindrical Ion Trap Array, 203
6.6. Field Applications of Mini-CITs, 204
6.7. Micro Ion Traps, 206
6.7.1. Single-Ion Study, 206
6.7.2. Optimization of Micro Ion Traps, 206
6.8. Conclusions, 207
References, 208
7 Gas Chromatography/Mass Spectrometry 211
7.1. Introduction, 212
7.2. Gas Chromatography, 213
7.2.1. Gas Chromatography/Mass Spectrometry, 213
7.2.1.1. Information Theory, 213
7.2.1.2. Informing Power in Mass Spectrometry, 214
7.2.1.3. Informing Power in Tandem Mass Spectrometry, 214
7.2.1.4. The State of the GC Market, 215
7.2.1.5. Carrier Gas, 215
7.2.2. The ITD Instrument, 216
7.2.2.1. Mass Analysis by Mass-Selective Instability, 217
7.2.2.2. Mode of Operation, 217
7.2.2.3. A Remarkable Achievement, 219
7.2.3. Ion Trap Mass Spectrometer, ITMS, 220
7.2.4. SATURN Model I Ion Trap Detector, 220
7.2.5. SATURN Model 4000 GC/MS System, 220
7.2.5.1. Ion Creation, 222
7.2.5.2. Ion Ejection, 222
7.2.6. Chemical Ionization, 225
7.2.6.1. Chemical Ionization Mass Spectral Mode, 225
7.2.6.2. Chemical Ionization with Specific Reagent
Ions, 228
7.2.7. Tandem Mass Spectrometry, 229
7.2.8. Scan Function for Tandem Mass Spectrometry, 230
7.3. Tandem Mass Spectrometric Determination of Dioxins and
Furans, 230
7.3.1. Tuning of the Mass Spectrometer, 233
7.3.2. Ionization, 233
7.3.3. Isolation of Mass-Selected Ion Species, 234
7.3.4. Resonant Excitation of Isolated Ion Species, 235
7.3.5. Analytical RF Ramp, 236
7.4. Comparison of Three Mass Spectrometric Methods, 236
7.4.1. Instruments, 237
7.4.2. Operational Conditions, 237
7.4.3. Product Ions Monitored, 238
7.4.4. Calibration, 239
7.4.5. Resonant Excitation, 239
7.4.6. Comparisons of Performances, 241
7.4.6.1. Ion Signals at Low Concentration, 241
7.4.6.2. Real Samples, 241
7.4.7. Ionization Cross Sections, 241
7.5. Conclusions, 245
References, 246
8 Ion Trap Mass Spectrometry/Liquid Chromatography 250
8.1. Introduction, 251
8.2. Electrospray Ionization, 252
8.3. Commercial Instrument Manufacturers, 252
8.3.1. Commercial Instrument Development, 253
8.3.2. Commercial Instrumentation, 254
8.4. Early Exploration of ESI Combined with a QIT, 254
8.4.1. Instrument Configuration, 255
8.4.2. Axial Modulation and Mass Range Extension, 256
8.5. Electrospray Mass Spectrum, 256
8.5.1. Charge State and Molecular Weight, 257
8.5.2. Computer Algorithms, 258
8.5.3. Ion Trap Extended Mass Range Operation, 258
8.5.4. Ion/Molecule Reactions, 261
8.5.5. MSn of Peptides and Proteins, 261
8.5.6. Positive Ion MS/MS and MSn Studies, 263
8.6. Recent Applications of ESI Combined with a QIT, 264
8.6.1. Major Nonlinear Resonances for Hexapole
and Octopole, 264
8.6.2. Ejection by a Dipole Field, 266
8.6.3. Ejection by a Hexapole Field, 267
8.6.4. Octopole Field, 267
8.6.5. Modified Hyperbolic Angle Ion Traps, 268
8.6.6. Combined Hexapole and Octopole Fields, 270
8.7. The HCT Ion Trap, 270
8.7.1. Ion Ejection, 272
8.7.2. Ion Trap Capacity, 272
8.7.3. Mass Resolution at High Scan Speeds, 272
8.7.4. Sensitivity for a Protein Digest, 274
8.7.5. De Novo Peptide Sequencing, 275
8.7.5.1. Protein Identification, 277
8.7.5.2. MOWSE Score, 277
8.7.5.3. Expectation Value, 277
8.7.6. De Novo Peptide Sequencing of Thirteen Proteins, 278
8.7.7. Multidimensional Liquid Chromatography, 278
8.8. Digital Ion Trap, 278
8.8.1. Introduction, 280
8.8.2. Concept of the DIT, 280
8.8.3. Stability Parameters, 281
8.8.4. Field Adjustment, 282
8.8.5. Trapping Ability, 282
8.8.6. Mass Resolution, 282
8.8.7. Pseudopotential Well Depth, 283
8.8.8. Forward and Reverse Mass Scans, 284
8.8.9. Summation of the Digital Ion Trap Development, 287
8.9. Conclusions, 287
References, 287
9 An Ion Trap Too Far? The Rosetta Mission to Characterize a Comet 291
9.1. Introduction, 291
9.2. The Rosetta Mission, 292
9.3. The MODULUS Ptolemy Experiment, 295
9.3.1. Stable Isotope Ratio Measurements for Light Elements, 296
9.3.2. The Ion Trap Mass Spectrometer as the Instrument of Choice, 296
9.3.3. Sample Processing and Isotope Ratio Measurements, 301
9.3.3.1. Ion Trap Operation, 301
9.3.3.2. Sample Processing and Analysis, 303
9.3.3.3. Operational Sequence at Cometary Encounter, 306
9.3.4. Summary and Conclusions, 307
Acknowledgment, 307
References, 307
Author Index 309