Objective: To establish a method for determination of the content of three alkaloids 3-methyl-canthin-5

6-dione

4-methoxy-5-hydroxycanthin-6-one and 4

5-dinethoxycanthin-6-one in Picrasmae Ramulus et Folium. Method: The determination was carried out with Phenomenex Gemini C18 column(4.6 mm×250 mm

5 μm). The mobile phase consisted of 0.25 mmol·L-1 ammonium acetate buffer(pH 4.0 by HAC)(A)-acetonitrile(B) with gradient elution. The detection wavelength was at 254 nm. Result: 3-methyl-canthin-5

6-dione

three reference substances were in good linearity between 0.004 56-0.182 40

0.012-0.480

0.002 6-0.104 0 μg(r≥0.999 9)

and the average recovery was greater than 96.72%(RSD＜0.78%). Conclusion: The determination method is simple and convenient

stable and repeatable

it would provided a reliable approach to evaluate and control the quality of Picrasmae Ramulus et Folium.