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The negative ion fast atom bombardment (NFAB) mass spectrometry of eight glycosidescontaining one to three sugar units have been studied. The mass spectra of NFAB exhibit morepredominant quasi-molecular ions without adduct ions in the high mass region, which indicate moreunambiguously the molecular weights of the glycosides, than the positive ion FAB (PFAB) spectrado. Among the three matrix substances tested, glycerol, thioglycerol and PEG-200, the last one wasfound to give the best results. The characteristic ions of NFAB collisional activation CNFAB-CA)spectra of [M-H]- ions were more abundant and gave more definite information about sequences ofthe sugar units than the corresponding PFAB-CA spectra of [M+H]~+ ions.
The negative ion fast atom bombardment (NFAB) mass spectrometry of eight glycosides con- taining one to three sugar units have been studied. The mass spectra of NFAB exhibit more dominant prime-molecular ions without adducts ions in the high mass region, which indicate moreunambiguously the molecular weights of the glycosides, than the positive ions FAB (PFAB) spectra do. Among the three matrix substance tested, glycerol, thioglycerol and PEG-200, the last one was found to give the best results. The characteristic ions of NFAB collisional activation CNFAB-CA) spectra of [MH] - ions were more abundant and gave more definite information about sequences of the sugar units than the corresponding PFAB-CA spectra of [M + H] ~ + ions.