Objective: To establish the method for determinnation of ephedrine hydrochloride、pseudoephedrine hydrochloride and methylephedrine hydrochloride in Qianbai Biyan Pian by capillary elctrophoresis. Method: The separation was performed on a fused silica capillary of 67 cm×75 μm (60 cm of effective elength). 130 mmol·L-1Tris-HCl-60% CH3OH(pH 9.27) was selected as the running buffer. The separation voltage was 20 kV. The samples was injected by gravity(10 s

15 cm). The detection wavelength was 210 nm. Result: The linear range of determination for ephedrine hydrochloride、pseudoephedrine hydrochloride and methylephedrine hydrochloride were 42.9-92.4

2.4-57.6

1.65-26.4 mg·L-1. The average recoveries were 99.7%

98.4%

95.6%

precisions of the method were 2.70%

2.76% and 2.52%(RSD

n=6). Conclusion: The method is convenient

rapid

accurate for the quality control of Qianbai Biyan Pian.