Effects of target identity and collision energy on the fragmentation of some mass-selected protonated neuropeptides.

A number of protonated neuropetides formed by 10 keV Cs+ ion bombardment are mass selected and their collision-induced dissociations (CID) with helium, argon, xenon and isobutane are monitored using a collision energy of 200 eV. Data obtained by fixing the collision gas and using translational energies in the range 50-250 eV are also presented. The present data imply that optimization of the CID spectra presented can be achieved through a judicious choice of both the target gas and the translational energy of the mass-selected ion. The combined effect of the two experimental parameters on the relative abundances of the major sequence ions and on the loss of side-chain moieties is discussed.