INVESTIGATION OF BEAM-INDUCED REACTIONS OCCURRING UNDER FAST-ATOM-BOMBARDMENT CONDITIONS BETWEEN TRIETHANOLAMINE AND VARIOUS PHOSPHOLIPIDS

The generation of adduct ions when using a triethanolamine (TEA) matri x under conditions of fast-atom bombardment has been investigated. in particular, phospholipids containing a free amino group react in the T EA matrix to form abundant adduct ions 26 and 42 mass units higher tha n the analyte pseudomolecular ions, The identity of these adduct ions was investigated using specific phosphatidylethanolamines and phosphat idylserine as well as 2-aminoethyldihydrogenphosphate and 2-aminoethyl monomethylphosphate as model compounds, Evidence obtained from positiv e- and negative-ion high-energy collision-induced dissociation tandem mass spectra, high resolution mass spectra, deuterium labelling and ex periments using diethanolamine/TEA mixtures revealed that the intensit ies of the adduct ions are dependent on the percentage of TEA in the m atrix and on the polarity of the analyte. The nature of the adduct ion s is best reflected by a structure in which a hydrogen atom of the fre e amino group is substituted by a vinyl (+ 26) or by an acetyl (+ 42) group, A mechanism for the adduct ion formation is proposed. (C) 1997 by John Wiley & Sons, Ltd.