Epimeric Separation of l-Ascorbic Acid and d-Isoascorbic Acid by Capillary Zone Electrophoresis

Publisher Website
Google Scholar
Abstract
Capillary zone electrophoresis (CZE) was used for separation of l-ascorbic acid (L-AA) and d-isoascorbic acid (D-IAA) in a model system. The effects of borate buffer concentration (0.05−0.25 M) and pH (pH 7.5−9.0) on migration time, resolution (Rs), and theoretical plates (N) were investigated. The migration times of L-AA and D-IAA increased with the increasing pH of carrier electrolyte (0.2 borate buffer), and the resolutions (Rs) of L-AA and D-IAA were calculated to be 12.98 at pH 9.0. Concentrations of borate buffer (pH 9.0) increased the Rs values of L-AA and D-IAA, and buffer concentrations >0.1 M were found to be effective for separation of L-AA and D-IAA. Methanol in the carrier electrolyte was also influential in improving the separation of L-AA and D-IAA, which increased with the increasing concentrations (0−10%) of methanol. The optimal separation conditions for L-AA and D-IAA were as follows: carrier electrolyte, 0.2 M borate buffer (pH 9.0); applied voltage, 25 kV, with an uncoated fused silica capillary, 75 μm (i.d.) × 57 cm. Keywords: Epimeric separation; l-ascorbic acid (L-AA); d-isoascorbic acid (D-IAA); capillary zone electrophoresis (CZE)
Keywords