A comparative study of two HPLC methods for dissolved monosaccharide analysis in seawater using 2-amino benzamide and 2-amino pyrazine as pre-column derivatization reagents

Two reversed-phase HPLC methods for molecular analysis of dissolved free monosaccharides in seawater were investigated comparatively by optimizing chromatographic separations and pre-column derivatization reactions. Monosaccharides derivatized with 2-amino benzamide or 2-amino pyrazine, and reduced with 2-picoline borane or 2-dimethylamino borane. According to results of optimization, separation performance, and detection limits, 2-amino benzamide method gave better results than 2-amino pyrazine method. Among 12 monosaccharides tested, it was possible to quantify glucose + galactose, galacturonic acid, glucuronic acid, xylose + arabinose, ribose, mannose, and N-acetyl-D-glucosamine with detection limits between 1.2 and 11 nM with intra-day repeatability of 2-9% and inter-day repeatability of 3-9%. The optimized method has the same level of detection limit with a widely used anion exchange chromatography method. Besides the preliminary results reported in this study, it may be possible to achieve higher sensitivity and to detect more monosaccharides by the use of shorter and narrow-bore columns at different polarities in further studies.