Selective determination of acidic carbohydrates using capillary electrophoresis

An analytical procedure has been developed for the selective determination of acidic carbohydrates in chemical pulps. Acidic mono- and oligosaccharides, commonly present as structural units in wood and pulp hemicelluloses, were derivatized at their carboxylic acid groups using sulfanilic acid. The resulting carbohydrate amide derivatives were separated by capillary electro- phoresis using a low pH phosphate buffer containing beta- cyclodextrin, and subsequently detected by their UV absorption at 247 nm. For D-glucuronic and D-galacturonic acid, a linear calibration range of at least two orders of magnitude and a minimum detection concentration of less than 3 mu M were obtained. The analytical procedure was employed in the separation of acidic xylooligosaccharides containing 4-O-Me-glucuronic and 4-deoxy-hex-4-eno-pyranosyluronic acid units obtained by enzymatic hydrolysis of kraft pulps.