Abstract: A reversed-phase high performance liquid chromatographic method (RP-HPLC) was developed for the simultaneous analysis of five isoflavonoids of Huangqi, the roots of Astragalus mongholicus. HPLC determination was performed on a Diamonsil C18 column (200 mm × 4.6 mm i.d., 5 μm) and detected at 230 nm. The mobile phase consisted of (A)acetonitrile and (B)water. Gradient program was adopted as follows: 0-25 min from 17%A to 31%A, 25-45 min 35%A. The flow rate was maintained at 1.0 mL/min. The method was proved to be linear in the ranges of 20.12-201.2 mg/L (r=0.9992), 4.62-46.2 mg/L (r=0.9997), 4.86-48.6 mg/L (r=0.9997), 9.24-92.4 mg/L (r=0.9995) and 6.92-69.2 mg/L (r=0.9995)for the five isoflavonoids, calycosin-7-O-β-D-glucoside, formononetin-7-O-β-D-glucoside, 9,10-dimethoxypterocarpan-3-O-β-D-glucoside, calycosin and formononetin, respectively. The recoveries were greater than 94%, and relative standard deviations were less than 3.2%. The method has been successfully applied to the simultaneous determination of the five isoflavonoids of radix astragali.

Key words: isoflavonoid, radix astragali , reversed-phase high performance liquid chromatography (RP-HPLC)