Simultaneous and sensitive HPLC determination of mono- and disaccharides, uronic acids, and amino sugars after derivatization by reductive amination

The reductive amination of low-molecular-weight saccharides, uronic acids, and amino sugars, followed by a separation of the derivates by means of ion-pair chromatography or RP-HPLC, offers an interesting alternative to HPAEC-PAD for the environmental analysis of these compounds. Under this aspect various potential amination reagents, i.e., p-aminobenzoic acid (p-AMBA), p-AMBA propyl ester, 1-aminopyrene, 2-(2-aminophenyl)indole, and 4-aminoazobenzene, were tested with regard to the formation of derivates and to the chromatographic properties of the formed derivates. p-AMBA, p-AMBA propyl ester and 4-aminoazobenzene proved to be especially suited, because they facilitate the amination of all carbohydrate reference components together with a complete separation and sensible detection (detection limits < 0.5 mg/L) of the derivates. Mainly the following elution sequence was ascertained: amino sugars (hexosamines) / disaccharide(s) monosaccharides (hexoses) hexuronic acid(s) N-acetyl-D-glucosamine. Detection limits down to 0.1 mumol/L were realized using p-AMBA as reagent, facilitating the determination of the target compounds in landfill leachates and lysimeter percolates. Applying the p-AMBA propyl ester for derivatization, chromatographic interferences with weakly retained derivates and the coelution of the reagent with its galactosamine derivate can be avoided, since the ester elutes after its derivates unlike p-AMBA itself.