Determination of Aristolochic Acids I and II in Herbal Medicines by High-performance Liquid Chromatography with Electrochemical Detection

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A high-performance liquid chromatography with electrochemical detection (HPLC-ECD) system has been developed for determining aristolochic acids I and II (AA1 and AA2). HPLC using an octadecylsilica (ODS) column and a mobile phase of methanol-water-phosphoric acid (65:35:0.5, v/v/v) was conducted for the separation of the AA1 and AA2. Both of the chromatographic peak heights for AA1 and AA2 at the detection potential of −0.7 V vs. Ag/AgCl were found to be linearly related to the concentrations injected, ranging from 10 ng mL−1 to 50 µg mL−1 (r > 0.997). The detection limits (S/N = 3) of AA1 and AA2 were 3.4 and 3.1 ng mL−1, respectively. Considering the detection limits, the present method makes it possible to be a purity test of the quantity of AA1 and AA2 contained as impurities in herbal medicines. The present HPLC-ECD was applied to determine AA1 and AA2 content in Radix et Rhizoma Asari and Radix Aristolochiae Fangchi.