Differentiation of Scutellariae Radix from Astragali Radix by capillary electrophoresis with electrochemical detection

Capillary electrophoresis with electrochemical detection (CE-ED) was employed for the differentiation of Scutellariae Radix from Astragali Radix. Scutellariae Radix contains a great deal of baicalin and baicalein that are not present in Astragali Radix, so both these crude drugs can be differentiated by determining their baicalin and baicalein content. The two analytes could be well separated within 8 min in a 40 cm length capillary with a separation voltage of 12 kV in a 100 mmol l(-1) borate buffer (pH 9.0). The working electrode was a 300 mu m diameter carbon disc electrode at a potential of 0.90 V (vs. SCE). The system demonstrated good long-term stability and reproducibility with an RSD of less than 5% for both migration time and peak current (n = 7). This proposed method has been successfully applied to analyze and identify the crude drugs with satisfactory assay results.