Quadrupole Storage Mass Spectrometry

Quadrupole Storage Mass Spectrometry RAYMOND E. MARCH AND RICHARD J. HUGHES Trent University Peterborough, Ontario, Canada with a historical review by John F. J. Tbdd University of Kent Canterbury, Kent, England WILEY A WILEY-INTERSCIENCE PUBLICATION JOHN WILEY & SONS New York / Chichester / Brisbane / Toronto / Singapore

CONTENTS CHAPTER 1. HISTORICAL REVIEW OF THE DEVELOPMENT OF THE QUADRUPOLE ION TRAP /. F. J. Todd 1 Introduction 1 1.1. Principles of Operation 2 l.ii. Utilization of the Quadrupole Ion Trap 6 (i) Mass-Selective Modes of Operation 6 (a) Mass-Selective Detection, 6 (b) Mass-Selective Storage, 13 (ii) Ion Loss Processes 16 (a) Unstable Trajectories, 17 (b) Interactions, 17 (c) Nonlinear Resonances, 21 (d) Self-Emptying, 22 1.111. The QUISTOR-Quadrupole Combination 22 l.iv. Theoretical Aspects of Ion Trap Operation 25 I.V. Research Activities with the Quadrupole Ion Trap 28 l.vi. Mass-Selective Ejection 30 CHAPTER 2. THEORY OF QUADRUPOLE MASS SPECTROMETRY 31 Introduction 31 2.1. Introduction to the Mathieu Equation 31 2.II. Stability Diagrams 37 2.III. The Complete Solution to the Mathieu Equation 39 2.IV. The Quadrupole Mass Filter 41 (i) Development of the Field Equations 42 xni

XIV CONTENTS (ii) Quadrupole Mass Filter Stability Diagram 44 (a) Mass Scanning, 47 (b) Resolution, 49 2.V. The Quadrupole Ion Trap (QUISTOR) 52 (i) Development of the Field Equations 52 (ii) Quadrupole Ion Trap Stability Diagrams 56 (a) Operating Modes, 57 (b) Derivation of the Parameters for Modes I, II, and III, 59 (c) Summary, 62 2.VI. Ion Motion in Quadrupole Fields 63 (i) Numerical Methods 63 (ii) Initial Value Problems 65 (iii) Boundary Value Problems 66 (iv) Matrix Methods 70 (v) Calculation of A, B, Cz n, and ß 71 2.VII. Ion Velocities and Kinetic Energies 74 (i) Introduction 74 (ii) Averaging of Trajectories 74 (iii) Psuedo-Potential Well Method 76 (iv) Phase-Space Dynamics 78 2.VIII. Matrix Methods and Phase-Space Dynamics for Modeling the Quadrupole Ion Trap 88 (i) Introduction 88 (ii) Matrix Methods 89 (iii) Phase-Space Dynamics 94 (a) EUiptical Boundaries in Phase-Space, 97 (b) Application to Quadrupole Device Modeling, 104 (iv) Examples of Practical Calculations 105 (a) Ion Transmission Efficiencies, 105 (b) Ion Energetics, 107 (v) Conclusion 110 CHAPTER 3. THE PHYSICS OF THE ION TRAP 111 Introduction 111

CONTENTS XV 3.1. Operational Modes of the Ion Trap 111 (i) Total Storage with In Situ Detection 112 (ii) Total Storage with Pulse-Out Analysis 114 (iii) Mass-Selective Storage with Pulse-Out Detection 117 (iv) Total Storage with Mass-Selective (Axial) Injection 123 3.II. Ion Trajectory Studies 126 (i) Trajectories in Two-Dimensional Quadrupole Fields 126 (ii) Trajectories in Three-Dimensional Quadrupole Fields 137 (iii) A Simulation Study 145 (a) Introduction, 145 (b) Description of the Program, 145 (c) Residts of the Simulation, 147 3.III. The Ionic Environment 161 (i) Introduction 161 (ii) An Introduction to Temporal Invariance 164 (iii) Space-Charge Effects 166 (iv) Temporal Invariance Formalism 168 (a) The Evolution of Statistical Properties in the Presence of Space Charge for a Specific Working Condition, 171 (b) Influence of the Drive Frequency on Space-Charge Phenomena, 175 (c) Inf luence of the Working Point, 175 (d) Influence of the Parameter q, 176 (e) Influence of the Parameters ß x,ß z, 176 (f) Summary, 179 3.IV. QUISTOR Resonant Excitation (QRE) 183 (i) Ionic Oscillations in the Ion Trap 183 (ii) QRE and the Argon System 186 (iii) Resonant Excitation and the Ion Chemistry of 2-Propanol 188 (iv) The Investigation of Space Charge within the Trap 191 3.V. Sample Calculations 196

XVI CONTENTS CHAPTER 4. CHEMISTRY IN THE QUADRUPOLE ION TRAP 209 Introduction 209 4.1. Bimolecular Processes 209 4.II. Proton Affinity Determination 217 (i) Experimental 218 (ii) Ketene 219 (iii) Diacetone Alcohol 220 (iv) Mesityl Oxide 221 (v) Isopropyl Acetate 222 4.III. Spectroscopy of Gaseous Ions 222 4.IV. Photochemistry of Gaseous Ions 224 (i) QUISTOR Photodissociation Studies 224 (ii) 2-Propanol 227 (a) Verification ofreaction Pathways, 232 (b) Isotopic Analogues of 2-Propanol, 234 (c) Structure of m/z 79: (CH 3 ) 2 CHOH H + OH 2, 235 (d) Ion Relaxation, 236 (iii) Mixed Associative Ions 239 (iv) IRMPD of Sulfur-Containing Ions 239 (a) Ethanethiol, 239 (b) 1-Propanethiol and 2-Propanethiol, 240 (c) 2-Hydroxyethanethiol, 241 (v) Isomer Differentiation by Multiphoton Dissociation 241 (vi) Photodissociation Rates 245 (vii) Wavelength Dependence of IRMPD 255 4.V. Photodissociation Using a Fiber-Optic Interface 257 4.VI. Confinement of Ions Injected into a Quadrupole Ion Trap 258 (i) Ion Injection with Delayed Trapping Potential under Collision-Free Conditions 260 (a) Pidsed Ion Injection, 260 (b) Concentric Ion Beam Injection, 264 (c) Pulsed Ion Injection with Interparticle Interactions, 265

CONTENTS xvn (ii) Ion Injection with Continuous Trapping Potential under Collision-Free Conditions 265 (iii) Ion Injection with Continuous Trapping Potential and Collisional Conditions 266 4.VII. Ejection of Ions Stored in a Quadrupole Ion Trap 269 CHAPTER 5. THE CYLINDRICAL ION TRAP 271 Introduction 271 5.1. Theoretical Treatments 272 5.II. Numerical Analysis 276 (i) Successive Displacement 278 (ii) Overrelaxation 278 (iii) Potential Distributions 279 5.III. Experimental Ion Storage Traps of Cylindrical Geometry 281 (i) Ion Storage Mass Spectra 282 (ii) Stability Diagram Determination 283 5.IV. Experimental Stability Diagrams and Mass-Selective Storage Mass Spectra 288 (i) Stability Diagrams 288 (ii) Mass-Selective Storage Mass Spectra 297 (a) Effect of Am Bias, 299 (b) Effect of Storage Time, 299 5.V. Secular Frequency of Ion Motion 303 5.VI. Influence of Space Charge on the Maximum Density of Stored Ions 305 5.VII. Applications of Cylindrical Ion Traps 305 (i) Mechanistic Studies 305 (ii) Metastable Ion Decay Processes 308 (a) Time-Resolved Photoionization Mass Spectrometry, 308 (b) Time-Resolved Cluster Ion Dissociation, 312 (iii) Laser Probing of Trapped Ions 313 5.VIII. Alternative Geometries for the Radio Frequency Quadrupole Ion Store 315

XV1H CONTENTS 5.IX. Ion Trapping Methods 318 5.X. Conclusion 319 CHAPTER 6. THE FINNIGAN MAT ION TRAP DETECTOR (ITD ) 321 Introduction 321 6.1. Ion Trajectory Control 321 6.II. Ion Trap Detector 323 (i) Gas Chromatography 323 (ii) Gas Chromatography/Mass Spectrometry 323 6.III. Review of Ion Trap Containment Theory 324 (i) Introduction 324 (ii) Description of the Instrument 325 (iii) Mathieu Equation and Stability Diagram 325 6.IV. Mass Analysis by Mass-Selective Instability 329 (i) Mass-Selective Instability; Mode of Operation 329 (ii) Effects of Low Molecular Weight Background Gas 331 (iii) Dynamic Range and Detection Limit 334 6.V. Operating Modes 336 (i) Chemical Ionization Mass Spectral Mode 336 (ii) Tandem Mass Spectrometry 339 (iii) The Ion Trap as a Tandem Mass Spectrometer 341 6.VI. Automatic Gain Control 344 (i) Mode of Operation 345 (ii) Dynamic Range with Automatic Gain Control 346 6.VII. Comparisons of the Performance of the Ion Trap Detector 350 (i) Methane Reagent Ion Population 350 (ii) Measurements of Urinary Organic Acids 350 (a) Quantitative Limits, 352 (b) Quantitative Metabolie Profiles, 352

CONTENTS XIX (c) Procedure for SmaU Sample Volumes, 354 (d) Conclusion, 357 (iii) Toxicological Application 357 (a) Sensitivity Limits, 357 (b) Sensitivity Comparison, 359 6.VIII. Miscellaneous Applications 359 (i) Direct Equilibrium Head-Space Analysis with an Ion Trap Detector 359 (ii) Gas Chromatograph-Fourier Transform Infrared Spectrometer-Ion Trap Detector System 360 (iii) Dications in the Ion Trap Detector 361 (iv) Isomer Distinction by Ion/Molecule Reactions 362 (v) Supercritical Fluid Chromatography and Mass Spectrometry with an Ion Trap Detector 362 6.IX. Conclusion 364 CHAPTER 7. ION TRAP MASS SPECTROMETER (ITMS ) 365 Introduction 365 7.1. Tandem Mass Spectrometric Mode 365 (i) Repetitive Tandem Mass Spectrometry 371 (ii) Chemical Ionization Tandem Mass Spectrometry 372 (iii) Isolation of a Single Ion Species in the Ion Trap 373 (iv) Removal of a Single Ion Species from the Ion Trap 378 (v) Internal Energy Control 378 7.II. Automatic Reaction Control 382 7.III. Comparison of Performance 383 (i) Comparisons of the Ion Trap Mass Spectrometer with the Triple Quadrupole Mass Spectrometer 383 (a) Collision-Induced Dissociation of Protonated Species, 383 (b) Energy-Resolved Mass Spectra, 384

XX CONTENTS (c) Daughter Ion Mass Spectra, 386 (ii) Comparison of the Ion Trap Mass Spectrometer with a Sector Instrument of Reverse Geometry 388 7.IV. Combined Application of DC and RF Voltages 389 (i) Specific Ion Reactor Mode 390 (ii) Ion Isolation from a Known Environment 391 (iii) Extension of the Mass Range of the Ion Trap Mass Spectrometer 394 7.V. Fourier Transform Ion Trap Mass Spectrometer 396 7.VI. Negative Ion Studies in the Ion Trap Mass Spectrometer 398 (i) Introduction 398 (ii) Early Negative Ion Trapping Studies 401 (iii) Negative Ion Storage Studies with an Ion Trap Mass Spectrometer 406 (a) Negative Ion Chemical Ionization Mass Spectrometry, 408 (b) Negative Ion Chemical Ionization Tandem Mass Spectrometry, 410 7.VII. Conclusion 414 References 415 Bibliography 445 Theses 443 APPENDIX PATENTS ON THE QUADRUPOLE ION TRAP 451 AUTHOR INDEX 457 CHEMICAL INDEX 459 SUBJECT INDEX 463