DISCRIMINATION OF PERMETHYLATED DISACCHARIDES BY THEIR CHEMICAL IONIZATION SPECTRA

Chemical ionization spectra of permethylated aldohexopyranosyl‐(1‐x)‐aldohexoses (x = 1‐6) with methane, isobutane, methanol and ammmonia as the reagent gases were studied. The chemical ionization methane spectra showed more pronounced differences related to different glycosidic linkages than the corresponding electron impact spectra. In contrast to the electron impact spectra, a reliable differentiation between (1–2) and (1–4) linked disaccharides could be achieved as well as a more detailed characterization of the stereoisomers in case of the (1–4) and (1–6) linked disaccharides. The chemical ionization isobutane spectra showed somewhat higher abundances for the [M+H]+ ions than with methane. It also methane. It also allows an easy differentiation of the various glycosidic linkages but its capability with respect to the discrimination of stereoisomers is inferior to that of methane. The base peak in chemical ionization ammonia spectra is [M+NH4]+, but the spectra are less characteristic than the above, although discrimination of the glycosidic linkages remains possible. Mass analysed ion kinetic energy and collisional activation spectra of selected ions of the chemical ionization spectra showed no characteristic differences, which excludes the possibility of using them as a means of differentiation for these compounds. Copyright © 1979 Heyden & Son Ltd