Abstract: Objective To establish a method for simultaneous determination of gallic acid, paeoniflorin, albiflorin, benzoyl paeoniflorin, saikosaponin A, saikosaponin C and saikosaponin D in the aqueous extract of Bupleurum and Paeoniae Alba by UPLC-PDA. Methods The Waters ACQUITY UPLC BEH C₁₈ (2.1 mm×100 mm, 1.7 μm) column was used with the mobile phase composed of acetonitrile - 0.1% acetic acid aqueous solution under gradient elution. The flow rate was 0.2 mL·min^-1 at detection wavelengths of 210 nm for saikosaponin A, saikosaponin C and saikosaponin D, 237 nm for paeoniflorin, albiflorin and benzoyl paeoniflorin, and 278 nm for gallic acid. The column temperature was 30℃ while the injection volume was 8 μL. Results The linear ranges of gallic acid, paeoniflorin, albiflorin, benzoyl paeoniflorin, saikosaponin A, saikosaponin C and saikosaponin D were 0.018~0.18 μg (r=0.999 9), 0.047~0.47 μg (r=1), 0.52~5.18 μg (r=0.999 9), 0.021~0.21 μg (r=0.999 9), 0.043~0.43 μg (r=0.999 9), 0.073~0.73 μg (r=0.999 9), and 0.042~0.42 μg (r=0.999 6) respectively. The average recovery (n=9) ranged from 99.94 to 101.47%, and the RSD was less than 2%. Conclusion This method is rapid, accurate and reproducible. It can be used for quality control of decoction of Radix Bupleuri-Paeoniae Alba.

Key words: bupleuri radix-paeoniae alba radix, paeoniflorin, saikosaponin A, herb pair, UPLC-PDA, determination