Abstract
Chemical ionization (CI) mass spectra with methane or isobutane reagent gas were measured in order to elucidate their characteristics for 41 nitrogen containing heteroaromatic compounds such as pyridine, quinoline, indole, pyrrole, pyrazine, pyrimidine, pyridazine, imidazole and their alkylsubstituents. The methane and isobutane CI mass spectra of these compounds gave the same ionic species as in alkylbenzenes except (M-28)+ in 2-propylpyridine and 2-(3-pentyl) pyridine. It was estimated that (M-28)+ was formed by McLafferty rearragement accompanying elimination of ethylene from the molecular ion. The ion abundance of each ion was fairly different compared with the case of alkylbenzenes, and it was remakable in terms of providing large ion abundance of MH+ based on high basicity of compounds. The fact that MH+ were the base peaks in all cases was very useful for the estimation of molecular weights.
