When glycosides were mixed with an appropriate amout of NaCl and LiCl, in the high mass region of their fast atom bombardment mass spectra appeared two strong ion peaks [M+Li]^+ and [M+Na]^+. This pair of adductions were easily recognized due to the fact that they were very strong (their abundances were higher than that of corresponding [M+H]^+ in several tens fold) and their mass difference was unite (16u). From these adductions, the molecular weight of glycosides may be difinitely determined. This technique was particularly suitable for analyzing glycosides with very weak [M+H]^+ in their FAB mass spectra. Six such glycosides have been analyzed by this means. This means have not been reported previously.

Key words: APPLICATION TECHNOLOGY, ALKALI METAL, FAB MASS SPECTROMETRY, GLYCOSIDE, ORGANIC NATURAL PRODUCTS, FRAGMENTS, AQUEOUS SOLUTION