Abstract
In-beam EI, CI and glycerol assisted SIMS spectra of three isomers of 1-methylcarbamoylpyridinium salts were investigated. The in-beam EI and SIMS spectra exhibited the intact 1-methylcarbamoylpyridinium cations at m/z 137. Thermal decomposition of the salts under in-beam EI conditions was found to give the volatile demetylated compounds as well as the hydrogenated and methylated neutral species which were similar to those observed in the FD spectra of 1-methyl-3-carbamoylpyridinium chloride. The major fragment ions of the salts under in-beam EI conditions were found to be derived from those species on the basis of the results obtained by single ion monitoring and linked field (B/E) scanning techniques. The comparison of the in-beam CI spectra with the corresponding EI spectra also clarified the thermally produced neutral species under in-beam conditions. SIMS spectra exhibited the intact 1-methylcarbamoylpyridinium cations as the base peaks and fragment ions at m/z 94, but did not exhibit any characteristic fragmentations for the structural isomers. From these results it is deduced that the 1-methylcarbamoylpyridinium cations observed in the in-beam EI spectra are mainly derived from the thermally hydrogenated species and the fragmentation processes of the cations are similar to those of SIMS.
