POSITIVE AND NEGATIVE FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY AND COLLISION SPECTROSCOPY IN THE STRUCTURAL CHARACTERIZATION OF MONOGLYCERIDES, DIGLYCERIDES AND TRIGLYCERIDES

The structural characterization of a selection of mono-, di- and triglycerides has been achieved by means of positive and negative ion fast atom bombardment (FAB) mass spectrometry combined with collision experiments. While FAB of the neat samples, without any liquid matrix, leads to the production of [M - (R - COO)]+ and [R - COO]- ions without any significantly abundant pseudo-molecular ions, samples dissolved in m-nitrobenzyl alcohol solution containing NaI give rise to abundant [M + Na]+ species together with the [M - (R - COO)]+ ions of high diagnostic value. Collisional experiments performed on the [M + Na]+ cations afford the identification of each acidic moiety constituting the glyceride. Preliminary attempts at the analyses of olive and seed oil were undertaken.