Separation and determination of levodopa and carbidopa in composite tablets by capillary zone electrophoresis with amperometric detection

A simple, reliable and reproducible method for separation and determination of levodopa and carbidopa based on capillary electrophoresis with amperometric detection is described in this paper. A potential of 900mV (versus Ag/AgCl 3mol/l KCl) was applied to the carbon disk electrode, which was used as working electrode in this system. Under the optimum conditions, two analytes were separated completely within 12min, with linear ranges of 1.2100.0 and 1.2-150.0µg/ml, and detection limits of 0.6 and 0.3µg/ml for levodopa and carbidopa, respectively. The mean recoveries of levodopa and carbidopa were 97.4 and 102.3%. The method was applied successfully to the determination in the real pharmaceutical samples.