Determination of active components in Radix Astragali and its medicinal preparations by capillary electrophoresis with electrochemical detection

A simple, fast, and reliable method based on capillary electrophoresis with electrochemical detection (CE-ED) was developed for the separation and determination of rutin, ferulic acid, vanillic acid, chlorogenic acid, quercetin and caffeic acid in Radix Astragali and its medicinal preparations. The effects of several important factors, such as detection potential, pH, running buffer concentration, separation voltage and injection time, were investigated to acquire the optimum conditions. Under the optimum conditions, the analytes could be separated within 17 min in a 75 cm length capillary at a separation voltage of 18 kV in a 10 mmol/L borate buffer (pH 8. 2). A 300 μm diameter carbon disk electrode generated a good response at + 0.95 V (vs. saturated calomel electrode (SCE)) for all analytes. The relationship between peak currents and analyte concentrations was linear over about three orders of magnitude with detection limits (S/N =3) ranging from 78 μg/L to 110 μg/L for all analytes. The average recoveries were 96.0% - 103.0% with the relative standard deviations of 1. 9% - 3.6% (n = 3). This method has been successful used for the determination of these analytes in real samples, and the assay results were satisfactory.