Collision‐Induced decomposition of peptides. An investigation into the effect of collision gas pressure on translational energy losses

The dependence on the gas pressure of translational energy losses, Δ E , suffered by incident ions in collision with helium target gas atoms was investigated for the [M + Na] + ion of valinomycin. Δ E was measured from the fragment ion peak positions in the mass‐analysed ion kinetic energy (MIKE) spectra. The variation of Δ E with target gas pressure was found to be different for different fragment ions. The implications of the results for the number of collisions which may occur under normal collision‐induced decomposition conditions (30–40% transmission) are discussed.