FRAGMENTATION RULES IN PLASMA DESORPTION MASS-SPECTROMETRY

Several studies concerning the analysis and quantification of biologic al and pharmaceutical compounds have been effected during the past 20- 30 years using different techniques of desorption-ionization. In most cases, however, the authors have not been interested in the mass spect rometric fragmentation mechanisms of these products. Plasma desorption mass spectrometry (PDMS) is a powerful technique for analysing, witho ut matrix interferences, solid biological and pharmaceutical compounds . In this work, we use PDMS in order to study the influence of the ami ne (amide) function on the fragmentation processes of nitrogen-contain ing compounds. For this work, quaternary ammonium salts, trisubstitute d amines, disubstituted amines and a compound with an amide function w ere chosen. Classical PD mass spectra, accurate mass measurements, tra nsitions in the field free region (FFR), labelled compound spectra and thermodynamical data are reported for the structural study of these c ompounds. Our results allow us to propose fragmentation rules for posi tively charged polyfunctional biological nitrogen compounds. These rul es relate to a class of structurally informative decomposition reactio ns that can be applied to the determination and of identification of s tructural unknowns.