CAPILLARY ELECTROPHORESIS OF CARBOXYLATED CARBOHYDRATES .3. SELECTIVEPRECOLUMN DERIVATIZATION OF GLYCOSAMINOGLYCAN DISACCHARIDES WITH 7-AMINONAPHTHALENE-1,3-DISULFONIC ACID FLUORESCING TAG FOR ULTRASENSITIVE LASER-INDUCED FLUORESCENCE DETECTION

Eight different glycosaminoglycan-derived disaccharides were selective ly labeled via their carboxylic acid group with 7-aminonaphthalene-1,3 -disulfonic acid (ANDSA) by a condensation reaction between the amino group of ANDSA and the carboxylic acid group of the saccharides in the presence of water-soluble carbodiimide. This derivatization reaction yielded stable derivatives with percentage yields as high as 97%. The ANDSA disaccharide derivatives were readily detected by on-column lase r induced fluorescence (LIF) with a He-Cd laser at 325 nm. With LIF, t he limit of detection was at the nanomolar level, three orders of magn itude lower than the limit of detection of underivatized disaccharides in the uv at 231 nm. In addition, due to the presence of two strong s ulfonic acid groups in the ANDSA tag, the derivatives were readily sep arated at acidic pH (i.e., pH 4.0-5.0) using 100 mM sodium acetate buf fers as the running electrolytes, The addition of polycationic spermin e in small amounts to the running electrolytes provided different sele ctivity with baseline resolution in the pH range 6.0-7.0, and the exce ss ANDSA migrated ahead of the ANDSA disaccharides. (C) 1997 Academic Press