Separation and identification of N-glycans from the stria vascularis. (a) An elution profile of diethylaminoethyl (DEAE) anion exchange HPLC. Samples extracted from the stria vascularis were analysed by chromatography. Peaks of compounds without sialylation (class N) and with a modification consisting of one to four sialic acid residues (classes A1 to A4) were detected. A signal between N and A1 peaks derived from non-glycan fluorescent materials7,28. (b) An elution profile of reversed-phase HPLC. We analysed the fractions isolated by DEAE chromatography [N and A1–A4; see (a)]. The numbers point to significant peaks (for the criterion, see Results). The traces marked by dashed red boxes in panels A1 and A2 are expanded in insets. Numerous peaks within the initial ~10 min were likely to contain chemical reagents including pyridylamine and its derivatives28.