Determining N-glycan Structures by HILIC-MS
Aliquots (1 µL) of the unlabeled portion of N-glycans released from samples were taken for permethylation analysis along with negative and positive controls (buffer, water, and fetuin). Unlabeled glycan samples were permethylated using methyl iodide in a dimethylsulfoxide (DMSO)/NaOH suspension for in-solution permethylation of glycans. Permethylated glycans were obtained from solution by extracting with chloroform, and samples were run on a Shimadzu-Biotech Resonance MALDI mass spectrometer using 10 mg/mL 2,5-dihydroxybenzoic acid (DHB) in acetonitrile as the matrix.