Use of graphitised carbon negative ion LC-MS to analyse enzymatically digested glycosaminoglycans

Capillary liquid chromatography-mass spectrometry using graphitised carbon stationary phase and ion trap mass spectrometry was shown to be a powerful technique for analysing glycosaminoglycans digested with endoglycosidases. Commonly found disaccharides from heparin/heparan sulphate digests at sub nanomole levels were found to be separated by mass and/or retention time and detected by negative ion electrospray mass spectrometry predominantly as [M - H](-) ions using a standard electrospray interface and flow rate between 6-10 mu L/min. Graphitised carbon liquid chromatography-fragmentation mass spectrometry provided sequence data of disaccharides and oligosaccharides. Sequence information was obtained from either collision of the [M - H](-) ions (low sulphated disaccharides) or of the [M + Na - 2H](-) ions (highly sulphated disaccharides). This separation and identification method of endoglycosidase digestion and sample preparation using a combination of cation exchange and graphitised carbon, was used to successfully analyse digests of keratan sulphate (keratanase) and heparin (heparinase) standards, and hyaluronic acid (hyaluronidase) from synovial fluid samples. (c) 2005 Elsevier B.V. All rights reserved.