Determination of saikosaponins by micellar electrokinetic capillary chromatography

In this study, we examine the feasibility of determining saikosapenins a, b1, b2, c and d, i.e., the bioactive components in Bupleuri Radix, using the micellar electrokinetic capillary chromatography technique. Results obtained from using different anion surfactants, bile salt or sodium dodecyl sulfate (SDS), are also compared. By using bile salt as a pseudostationary phase, the baseline separation of saikosaponins is observed; however, the detection limit is unfavorable. Whereas the baseline resolution of saikosaponins is achieved after adding γ-cyclodextrin in the SDS running buffer. In addition, another separating method is developed with the mixed micellar system of SDS and Brij 35 containing γ-cyclodextrin. The contents of saikosaponins in traditional Chinese medicinal prescriptions, such as Sheau Chair Hwu Tang, Bupleuri Radix plant and Chair Hwu San are analyzed by one of the above methods. The entire separation can be completed within 9 min by these methods. The R.S.D. values of the migration times are all below 1%. Moreover, the detection limits of saikosaponins vary from 7 to 33 μg/ml.