Figure 3.

ESI-MS/MS spectra recorded in negative ion mode of various single unsulfated saturated chondroitin oligosaccharide species, in particular disaccharide (A), tetrasaccharide (B), hexasaccharide (C), octasaccharide (D), dodecasaccharide (E), and 16-mer oligomer (F), separated by means of RPIP-HPLC. See also Table 1 for the calculated MS/MS C₁ product ions derived from specific precursor ions. The inset in (A) shows the nomenclature for disaccharide fragmentation proposed by Domon and Costello.¹⁴ Ions that contain a non-reducing terminus are labeled with upper-case letters from the beginning of the alphabet (A, B, C), and those that contain the reducing end of the oligosaccharide are labeled with letters from the end of the alphabet (X, Y, Z). Subscripts indicate the cleaved ions. The A and X ions are produced by cleavage across the glycosidic ring, and are labeled by assigning each ring bond a number and counting clockwise. Ions produced from cleavage of successive residues are labeled A_m, B_m, and C_m, with m=1 for the non-reducing end, and X_n, Y_n, and Z_n, with n=1 for the reducing-end residue.