CAPILLARY ZONE ELECTROPHORESIS OF P-AMINOBENZOIC ACID-DERIVATIVES OF ALDOSES, KETOSES AND URONIC-ACIDS

Aldoses, ketoses and uronic acids were derivatized with p-aminobenzoic acid and separated as their borate complexes by capillary zone electr ophoresis, using a capillary tube of fused silica containing 150 mm bo rate buffer, pH 10.0, as carrier. The electrophoretic mobilities of 22 carbohydrates were determined and found to increase with increasing s tability of the borate complexes formed. Besides the number of hydroxy l groups and the presence of substituents, complex stability depended most strongly on the configuration of the three vicinal hydroxyl group s at C2, C3 and C4. On-column UV monitoring at 285 nm allowed the dete ction of glucose with a lower mass detection limit of 15 fmol and a co ncentration sensitivity of 4 mum. Reproducible quantification of carbo hydrates was achieved at least in the concentration range of 0.1-10 mm in reaction solutions by the relative peak area method, using cinnami c acid as internal standard. The method was applied successfully to th e determination of the monosaccharide composition of polysaccharides e xtracted from Radix althaeae.