Objective: To develop an HPLC method for simultaneous determination of uridine

adenosine

guanosine and epigoitrin in Radix Isatidis

and compare the content variation of the four components of herbs harvested at different time. Method: Four components were separated by Kromasil C18 column (4.6 mm×250 mm

5 μm) with gradient mobile phase of methanol-0.1% phosphoric acid at the flow rate of 0.7 mL ·min-1. The detection wavelength was set at 254 nm (0-30 min) and 245 nm (30-45 min). The column temperature was maintained at 25℃. Result: The calibration curves of uridine

adenosine

guanosine and epigoitrin were in good linearity over the range of 14.80-1 184 ng (r=0.999 9)

14.55-1 164 ng (r=0.999 9)

13.75-1 100 ng (r=0.999 9)

12.25-980 ng (r=0.999 9)

respectively. The average recoveries of the four components were 99.5% (RSD 1.2%)

98.3% (RSD 1.4%)

98.1% (RSD 1.2%)

99.0% (RSD 0.9%)

respectively. The content of four components in Radix Isatidis varied with different harvest time. Conclusion: The method is simple

accurate and reproducible for quality control of Radix Isatidis.