Analysis of saikosaponins in Bupleuri Radix and Caihu-shugan-san using reversed-phase HPLC with pulsed amperometric detection.

A simple and sensitive reversed-phase (RP) HPLC coupled with pulsed amperometric detection (PAD) method was developed to determine the saikosaponin content in Bupleuri Radix or Caihu-shugan-san. Four saikosaponins in Bupleuri Radix and Caihu-shugan-san were extracted with a 6:4 solution of 10 mM sodium phosphate buffer (pH 8)/100% ethanol. Pulsed amperometric detection of carbohydrates in four major saikosaponins was highly sensitive when used with a water-acetonitrile gradient on an alkaline RP column with a post-column delivery system. The limits of detection (S/N=3) and of quantification (S/N=10) of saikosaponins were 0.01-0.02 and 0.03-0.05 μg/mL, respectively. The intra- and inter-day precision (RSDs) were each <9.7% and the average recoveries were 95.0-97.6% in Bupleuri Radix. This method can be used to analyze saikosaponins in Bupleuri Radix and Caihu-shugan-san.