Determination of Carbohydrates by Capillary Zone Electrophoresis with Amperometric Detection at a Copper Microelectrode

Capillary zone electrophoresis (CZE) was employed to separate sugars according to their electrophoretic mobilities In strong alkaline solutions (pH ca. 13). Saccharide zones were monitored electrochemlcally using amperometric detection at a constant potential, 0.6 V (vs Ag/AgCl), with a cylindrical copper wire electrode (25 µm in diameter). The Cu-wlre microelectrode In strong basic solutions had electrochemical behavior similar to that of Cu electrodes with larger dimensions and appeared to show no deterioration for hundreds of runs. A sample mixture containing 15 different sugars was separated In less than 45 min with separation efficiencies up to 200 000 theoretical plates. The calibration plot was found to be linear over 3 orders of magnitude and the limits of detection for the saccharides studied were In the femtomole range.