Figure 3: (a) Base peak chromatogram of LC-MS analysis of chymotryptic N-glycopeptides purified by ZIC-HILIC. The peaks at 27.30 min, 29.85 min, 37.47 min, 38.22 min and 41.47 min are the primary glycopeptides. (b) Extracted ion chromatogram of oxonium fragment ion at m/z 366 (GlcNAc-Gal) from CID MS/ MS spectra. (c) Summed mass spectrum at 37.60-38.60 min revealed some major N-glycopeptides.