Separation of a complex mixture of heparin-derived oligosaccharides using reversed-phase high-performance liquid chromatography

A reversed-phase ion-pairing high-performance liquid chromatography (RP-HPIPC) method for the separation of a complex mixture of heparin-derived oligosacchrides has been developed by a stepwise optimization of the mobile phase, in which the concentration of ion-pairing reagent, mobile phase pH, and acetonitrile concentration were varied. The resolution of more than 30 oligosaccharide components was obtained, under optimized conditions, in an analysis time of less than 30 min. This represents the first RP-HPLC method that can separate a complex mixture of both small and large sulfated oligosaccharides in a single chromatographic step. The heparin-derived oligosaccharides, in this mixture, can also be separated under a second set of RP-HPIPC conditions using a volatile ion-pairing reagent, tributylammonium acetate, to aid in the recovery of individual sulfated oligosaccharides. Moreover, it was possible to replace sodium chloride gradient, required for eluting highly sulfated oligosaccharides, with a fixed, low concentration of a volatile salt, ammonium acetate, by utilizing an acetonitrile gradient. This solvent system might make it possible to directly interface this RP-HPIPC separation with mass spectral analysis.