Fragmentation rules in plasma desorption mass spectrometry

Several studies concerning the analysis and quantification of biological 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 spectrometric fragmentation mechanisms of these products. Plasma desorption mass spectrometry (PDMS) is a powerful technique for analysing, without matrix interferences, solid biological and pharmaceutical compounds. In this work, we use PDMS in order to study the influence of the amine (amide) function on the fragmentation processes of nitrogen‐containing compounds. For this work, quaternary ammonium salts, trisubstituted amines, disubstituted amines and a compound with an amide function were chosen. Classical PD mass spectra, accurate mass measurements, transitions in the field free region (FFR), labelled compound spectra and thermodynamical data are reported for the structural study of these compounds. Our results allow us to propose fragmentation rules for positively charged nonfunctional biological nitrogen compounds. These rules relate to a class of structurally informative decomposition reactions that can be applied to the determination and of identification of structural unknowns.