Capillary electrophoretic examination of underivatized oligosaccharide mixtures released from immunoglobulin G antibodies and CTLA4Ig fusion protein

A procedure is presented for the separation of underivatized oligosaccharides by capillary electrophoresis (CE) with a phytic acid-berate buffer system. The presence of the phytic acid ion-pairing agent greatly increases resolution between oligosaccharides in the complex mixtures studied, which was demonstrated by the separation of oligosaccharides originating from various immunoglobulin G antibodies and CTLA4Ig, a biologic fusion protein. The conditions also resolve neutral oligosaccharides, usually a major CE limitation. High-performance anion-exchange chromatography with pulsed amperometric detection, a standard technique for oligosaccharide and sugar analysis, is used as a reference method to analyze some of the complex oligosaccharide mixtures.