Tandem mass spectrometry: dissociation of ions by collisional activation

This review presents a brief historical introduction to the development of tandem mass spectrometry and its principal applications. It is placed in th e context of the general principles underlying mass spectrometry, particula rly the relationships between internal energy and fragmentation kinetics. T he center-of-mass framework is presented as a convenient means of applying conservation of momentum to the energy transfer problem in tandem mass spec trometry as a means of deducing energy transfer in the collisional activati on step and kinetic energy release as activated ions dissociate into fragme nt ions and neutrals, The principles of molecular beam methods are summariz ed and illustrative examples are given for which definitive information on reaction dynamics is available. The importance of scattering-very little ap preciated in early discussions of tandem mass spectrometry-is shown to be t he natural consequence of impulsive collisions, which appears to be a gener al mechanism for energy exchange in collisional activation. It is shown tha t the average energy transferred in single collisions is much less than the theoretical maximum given by the center-of-mass collision energy and the M assey criterion is presented as a simplistic rationale for understanding th e essentially exponential decline in the energy transfer function above and below the relative velocity at which the probability for energy transfer i s maximized, The issues of energy transfer in collisions of large molecular ions with low-mass neutrals are reviewed and a general description of ener gy transfer in multiple collisions is presented. It is shown that the cente r-of-mass and Massey criterion limitations are pragmatically overcome bai m ultiple collision activation in ion traps, Surface-induced dissociation is presented as a viable alternative to multiple collision activation which is especially attractive for activation of large molecular ions. Finally, a f ew of the emerging dynamics principles governing energy transfer and dissoc iation of peptides are summarized. Copyright (C) 2000 John Wiley & Sons, Lt d.