Characterization of carbohydrates using a combination of derivatization, high-performance liquid chromatography and...

A combination of derivatization methods, chromatographic techniques and mass spectrometric ionization modes have been explored for the characterization of small sugars and medium-size oligosaccharides. Derivatization using 1-phenyl-3-methyl-5-pyrazolone (PMP) was preferred over pyridylamination (PA) owing to the simplicity of the reaction method, and also to enhanced ionization efficiency of the PMP derivatives relative to aminopyridyl sugars. The good quality and ease of separation of PMP derivatives by high-performance liquid chromatography were also advantages of using PMP derivatization rather than pyridylamination. PMP- and PA-monosaccharides produced abundant ions by either fast atom bombardment (FAB), electrospray ionization (ESI) or matrix-assisted laser desorption/ionization (MALDI). The PA and PMP derivatives of lactose, fucosyllactose and sialyllactose yielded FAB spectra with low S/N ratios, whereas ESI and MALDI produced better spectra with a hundredth of the material used for FAB. In general, PMP derivatives of these di- and trisaccharides gave rise to stronger signals than PA analogs. For Oligosaccharides containing more than three sugar rings, only PMP was used for derivatization, FAB was dropped and only ESI and MALDI were utilized.