Derivatization of peptides to enhance ionization effiency and control fragmentation during analysis by fast atom bombardment tandem mass spectrometry

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Abstract
Novel and simple procedures for preparing ethyl‐triphenylphosphonium derivatives of peptides are described. These procecores allow an ethyl‐triphenylphosphonium moiety to be selectively attached to either the N‐ or C‐terminus. The resulting derivatives contain a positive charge at a fixed position and have significant hydrophobic character. Modification of peptides by these chemical methods significantly enhances the efficiency of fast atom bombardment ionization, especially of hydrophilc peptides. Moreover, upon collisionally activated dissociation, the deriva‐tized peptides generate a predictable series of sequence ions from either the C‐terminus or the N‐terminus, depending on the location of the ethyl‐triphenylphosphonium moiety.