3.5. Structural determination of oligosaccharides by negative-ion ESI–
CID–MS/MS The ESI–CID–MS/MS experiment was conducted using molecular ions as precursors. Results are shown in Fig. 3. For fraction I (Fig. 3A), the glycosidic fragment ions (B2+Na at m/z 473 and C2+Na at m/z 491) indicated the existence of a nonsulphated fucose residue. However, the positions of two sulphate groups were ambiguous. Saccharide ring1,4A cleavage is characteristic of a 3-linkage for a fucose residue (Chen et al., 2008). Two consecutive