Determination of paeonol and paeoniflorin in Chinese medicine Cortex Moutan and 'Shuangdan' granule by micellar electrokinetic capillary chromatography.

An easy, simple and rapid micellar electrokinetic capillary chromatography (MEKC) method was developed for the separation of two active components paeonol (PN) and paeoniflorin (PF) within 7 min. Capillary electrophoresis (CE) was performed using a 50.0 cm (42.0 cm to the detector window) x 75 microm i.d. fused-silica capillary. The optimal running buffer containing 10mM borate and 25 mM SDS at pH 9.54 was employed. The applied voltage 15 kV and the temperature 25 degrees C was used in CE separation. The linearities between peak areas and the concentrations of the analytes were investigated, and they exhibited excellent linear behavior over the investigated concentration ranges (R(2): 0.9945 for PN and 0.9992 for PF). The method was successfully applied to the determination of these two components contained in Cortex Moutan and 'Shuangdan' granule. The average recoveries ranged between 97.6 and 105.3% for PN and 95.3 and 106.1% for PF, respectively.