Fast and Sensitive LC-DAD-ESI/MS Method for Analysis of Saikosaponins c, a, and d from the Roots of Bupleurum Falcatum (Sandaochaihu)

In the present study, we developed a liquid chromatography-diode array detector-electrospray ionization/mass spectrometric (LC-DAD-ESI/MS) method for analysis of saikosaponins in Bupleurum falcatum. The LC method employed a ZORBAX SB-Aq analytical column (150 x 4.6 mm i.d., 5 mu m) at a flow rate of 0.8 mL/min coupled with a diode array detector at 204 nm. A step gradient of acetonitrile-water (v/v) containing 0.5% formic acid from 30 to 70% was applied, leading to a sample analysis time of 30 min. The ESI-MS was carried out in positive and negative modes from 500 to 1,500 m/z. Saikosaponins c, a, and d gave strong sodium adducts at m/z 949.6, 803.5 and 803.6, respectively, in positive mode. The data indicate that the present LC-DAD-ESI/MS assay is an effective method for the determination of saikosaponins c, a and d from the roots of Bupleurum falcatum.