Development and application of a sensitive phosphonium-hydrazide oligosaccharide labelling reagent in capillary electrophoresis- electrospray ionization- mass spectrometry

•(4-hydrazidebutyl) triphenylphosphonium bromide for oligosaccharides labelling.•Labelled oligosaccharides could be separated well in positive ion mode CE-MS.•Signal intensity of labelled oligosaccharides could be enhanced significantly in MS.•Combine CE-MS separation and identification with MALDI-MS high throughput screening.