[Simultaneous determination of four compounds in Erzhiwan by HPLC].

To establish an HPLC method for simultaneous determination of nuzhenide, specnuezhenide, wedelolactone and oleanic acid in Erzhiwan. The DIKMA C18 (4.6 mm x 200 mm, 5 microm) column was adopted with acetonitrile and 0.1% phosphoric acid solution as the mobile phase and gradient elution. The flow rate was 1.0 mL x min(-1) and the volume of injection was 20 microL. The column temperature was maintained at 30 degrees C and the detective wavelength was set at 215 nm. There were good linear relationships between the peak area and concentration at the range of 2.008-80.32 (r = 0.999 6), 5.872-234.88 (r = 0.999 7) , 0.9-36 (r = 0.999 9), 13.24-529.6 mg x L(-1) (r = 0.999 6) for nuzhenide, specnuezhenide, wedelolactone and oleanic acid, respectively. The average recovery rates of nuzhenide, specnuezhenide, wedelolactone and oleanic acid were 99.25%, 98.70%, 96.23% and 101.5%, respectively, with RSD of less than 3%. The established method was so easy, rapid and accurate that it can be used as an effective way for quality control of Erzhiwan.