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 bombardme nt are mass selected and their collision-induced dissociations (CID) w ith 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 optimzation 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 majo r sequence ions and on the loss of side-chain moieties is discussed.