Factors affecting the fragmentation of peptides in fast atom bombardment mass spectrometry.

Positive ion fast atom bombardment mass spectra of a series of biologically active peptides were obtained in order to ascertain conditions that contribute to an increase in fragment ion abundance of such peptides. The effect of derivatization, hydrophobic character and the presence of acid in the matrix on fragmentation of peptides were all investigated. It is shown that a substantial increase in fragment signal ion abundance is observed when mineral acid is present in the matrix, and is in accord with the gas-phase collision model proposed by Kebarle.