Abstract: Xylobiose and xylotriose were separated from xylooligosaccharides produced by xylanase from corncob xylan by gel permeation chromatography on polyacrylamide gel Bio-Gel P-2 by FPLC system. High purities of xylobiose (about 97%) and xylotriose (about 94%) were obtained by twice separation on Bio-Gel P-2. The structures of xylobiose and xylotriose were determined by HPLC, electrospray ionization mass spectrometry(ESI-MS)and ¹³C NMR spectroscopy. The results showed that the molecular weights of xylobiose and xylotriose were 282 and 414, respectively, and there were no substitutions of 2-O- or 3-O-acetyl, arabinose,or 4-O-methylglucuronic acid. According to the structure of corncob xylan, the xylobiose and xylotriose prepared by xylanase from corncob xylan were β-D-(1→4)-xylopyranosyl-(14)-D-xylopyranose and β-D-(1→4)-xylopyranosyl-(1→4)-D-xylopyranose-(1→4)-D-xylopyranose,respectively without any substitution.

Key words: xylobiose, xylotriose, electrospray ionization mass spectrometry