Objective: To establish the method for determining the content of berberine in traditional Chinese medicine with online solid phase extraction-HPLC. Method: Using one of the dual gradient pumps to enrich and purify the sample solution

then wash the aimed analyte into analytical column by switching the valve to another position after removing of matrix interference substance. Silica-based strong cation exchange column (300 Å

4.6 mm×50 mm) was used as online-SPE column with a mobile phase consisting of acetonitrile-500 mmol ·L-1 ammonium acetate in a gradient elution. Acclaim C18(4.6 mm×250 mm

5 μm) was used as analytical column with a mobile phase of acetonitrile-30 mmol ·L-1 KH2PO4 at a flow rate of 1.0 mL · min-1. UV detection wavelength was set up at 345 nm. Result: There is a good linear relationship(r=0.999) within the concentration range of 1.24-124 mg · L-1. The average recovery was 99.5%. Conclusion: This method was simple

fast and has a better speciality. The results of determination were reliable and reproducible by validating for accuracy

precision and reproducibility.