A simple method for the simultaneous determination of four bioactive components (puerarin, daidzein, baicalin, and wogonin) in composite preparations by microemulsion capillary electrophoresis with UV detection has been developed for the first time. A running buffer composed of 8% acetonitrile + 4% microemulsion(3.24% n-heptane + 13.24% sodium dodecyl sulfate (SDS) + 26.44% n-butanol + 57.08% distilled water in weight ratio) + 20 mM borax solution was found to be the most suitable for this separation. The limits of detection for four analytes were over the range of 0.50 - 1.2 μg ml-1. In the tested concentration range, linear relationships (correlation coefficients: 0.997 for baicalin, 0.997 for wogonin, 0.998 for daidzein and 0.999 for puerarin) between the peak areas and the concentrations of the analytes were obtained. This method has been successfully applied to simultaneous determination of the four bioactive components with recoveries from 94.6 to 106.3%.

Cunhong Li and Yan Xu