An Introduction to Quadrupole Ion Trap Mass Spectrometry

A concise introduction is presented to the theory and application of quadrupole ion trap mass spectrometry. The presentation of the theoretical treatment is based on a demonstration of the equivalence of the force acting on an ion in a quadrupole field and the force derived from the Mathieu equation; this equivalence permits the application of the solutions of Mathieu’s equation to the confinement of gaseous ions. Resonant excitation, collision-induced dissociation, mass spectrometry, tandem mass spectrometry and chemical ionization are discussed in the context of analytical applications. Sample calculations of the trapping parameters qz and βz, the axial secular frequency, mass range, mass range extension and the magnitude of the potential well depth are given. © 1997 by John Wiley & Sons, Ltd.