Abstract: Vanillin, vanillin alcohol, vanillin acid, and ferulic acid were determined simultaneously by capillary electrophoresis. The effects of composition, pH and concentration of the running buffer, separation voltage, injection time, and detection wavelength on separation efficiency were investigated with the aim of establishing optimum detection conditions. Four analytes were well separated under the optimized conditions: a fused silica capillary as separation channel, working voltage of 20 kV, detection temperature of 20 ℃, injection time of 5 s, detection wavelength of 280 nm and Na2B4O7-H3BO3 solution (30 mmol/L, pH 9.23) as running buffer. This method has been successfully applied to analyze Radix Angelicae sinensis, Rhizoma Picrorhizae and toffee.

Key words: capillary electrophoresis, separation, vanillin, vanillin alcohol, vanillin acid, ferulic acid