Comparison of thermally-assisted fast atom bombardment (TA-FAB) with conventional FAB and EI mass spectrometry for the analysis of the Helminthosporium carbonum mycotoxins.

A new technique known as thermally-assisted fast atom bombardment (TA-FAB) has been applied to the analysis of a series of cyclic tetrapeptide mycotoxins in order to demonstrate the usefulness of the method for structural elucidation. TA-FAB uses saturated aqueous solutions of highly hydroxylated compounds, such as fructose, as alternatives to the usual viscous liquid matrices employed in conventional FAB. During the TA-FAB analysis, the probe tip is resistively heated causing differences to occur in the desorption profiles for the analyte and the matrix ions enabling an optimization for analyte desorption as a function of temperature. In this study, direct comparisons are made between TA-FAB, conventional FAB, and electron impact ionization for the analysis of the Helminthosporium carbonum mycotoxins at the 1.5 micrograms level. The results demonstrate the superior capacity of TA-FAB to provide both molecular weight confirmation and significant fragmentation to aid in the structural elucidation of these important biomolecules.