AbstractThe negative secondary ion mass spectrometry, in combination with the stereoselective derivatizations with substituted boronic acid RB(OH)2, was used in the analysis of fourteen oligosaccharides. The mass spectra of the derivatives provide information on their linkage positions and isomerism of the individual monosacaccharide units. The results indicated that among the derivatives of the oligosaccharides analyzed, those with 1–4 and 1–6 linkages all presented the ion peaks atm/z287, sometimes one more peak atm/z449. Furthermore, a relationship was found between the linkage positions and the intensity orders of the derivative ions. Finally, the derivatives of the disaccharides with a galactose presented an intense ion peak atm/z347, and those of oligosaccharides with 1–6 linkage to a galactose at terminal presented the ion atm/z317. In the case of oligosaccharides with a fructose residue, characteristic ion ofm/z155 was produced. The conditions of stereoselective derivatizations and mass spectrometry were studied, in order to obtain a better reproducibility of the mass sp