Abstract: The accurate assay of the three highly hydrophobic ginsenosides Rg1, Re and Rb1 in one injection plays a key role in assessing the quality of Panax quinquefolius. A micellar electrokinetic capillary chromatographic (MEKC) method was therefore developed for the simultaneous determination of ginsenosides Rg1, Re and Rb1 in Panax quinquefolium. The separation was carried out on an uncoated fused-silica capillary with 50 μm i.d. and 30 cm effective length (to the detector). The separation buffer was V(15 mmol/L Na2B4O7+30 mmol/L H3BO3 (pH 9.0)+100 mmol/L dodecyl sulfate sodium salt (SDS)+30 g/L polyethylene glycol (PEG) 35000):V(methanol):V(iso-propanol)=2:1:1. The separation voltage was 30 kV with hydrodynamic injection at 3.448 kPa for 15 s. The detection wavelength was set at 214 nm. The factors such as the buffer concentration, the content of the organic solvent and buffer additives, which influenced the accurate analysis of ginsenosides, were investigated in detail. The samples were simply extracted twice by methanol-10 mmol/L SDS (1:1, v/v). The limits of detection (LOD, S/N=3) for Rg1, Re and Rb1 were 30, 40 and 30 mg/L, respectively. The limits of quantitation (LOQ, S/N=9) were 90, 120 and 90 mg/L, respectively. The recoveries at the studied concentrations were between 87.4% and 95.2%. The established method was used for the determination of the certified reference material (CRM) of Rg1, Re and Rb1 in Panax quinquefolium. The results were in good agreement with those of the high performance liquid chromatographic (HPLC) method. The samples of Panax quinquefolium from Canada, United States and China were also analyzed separately and satisfactory results were obtained.

Key words: ginsenosides, high performance liquid chromatography （HPLC）, Panax quinquefolium, micellar electrokinetic capillary chromatography （MEKC）