Sialylated N-glycans
A large portion of the identified tears N- glycans beared a sialic acid as terminal antennary residue, with the two typical diagnostic fragments observed by MS/MS at m/z 847.4 and at m/z1021.5, corresponding to the sialylated lactosamine epitope, and to fucosylated homologous (sLex/a motif), respectively.