A new method for quantitative determination of two uronic acids by CZE with direct UV detection

A new method using capillary zone electrophoresis was developed for the rapid quantification of two common uronic acids, galacturonic acid and glucuronic acid, based on utilization of an alkaline background electrolyte with reversed electroosmotic flow (EOF) within 16 min. The method relies on in-capillary reaction and direct UV detection at the wavelength 270 nm. The optimum electrolyte solution was prepared of 130 mm sodium hydroxide, 36 mm disodium hydrogen phosphate dihydrate and 0.5 mm cetyltrimethylammonium bromide. EOF was reversed to detect uronic acids and to improve the separation of neutral sugars. The established method was validated and the results showed good linearity, high precision and satisfactory sensitivity. The newly developed method was successfully applied to analyze galacturonic acid and glucuronic acid content in Forsythia suspensa polysaccharides. The method is fast since only sample hydrolysis and dilution are required in the sample preparation.