[Simultaneous determination of five isoflavonoids in commercial Radix Astragali by high performance liquid...

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 x 4.6 mm i.d., 5 microm) 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. 999 5) for the five isoflavonoids, calycosin-7-O-beta-D-glucoside, formononetin-7-O-beta-D-glucoside,9,10-dimethoxypterocarpan-3-O-beta-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.