POSITIVE-ION LIQUID SECONDARY-ION MASS-SPECTRA OF AROMATIC SULFONIUM SALTS

Organic sulfonium salts exist as pre-charged species in the matrices n ormally used for liquid secondary ionization mass spectrometry. Positi ve ion LSIMS mass spectra of the sulfonium salts therefore exhibit the intact cation (C+) as the dominant ion species. Generally, the fragme nt ions are of 30-40% relative intensity and are formed through simple cleavages and rearrangements. Cluster ions such as CAC(+) and C(3)A(2 )(+) are also present in the mass spectra (A is the counter ion of the salt). These cluster ions provided confirmation of the molecular weig ht. Adduct ions are formed between organic sulfonium salts and matrice s used in LSIMS such as diethanolamine and triethanolamine. Beam-induc ed reactions are identified by comparison of mass spectra obtained wit h electrospray ionization, and by changes in ion products with changes in solvent matrix.