Fast separation and determination of coumarins in Fructus cnidii extracts by CEC using poly(butyl methacrylate-co-ethylene dimethacrylate-co-[2-(methacryloyloxy)ethyl] trimethylammonium chloride) monolithic columns.

A rapid CEC method with poly(butyl methacrylate-co-ethylene dimethacrylate-co-[2-(methacryloyloxy)ethyl] trimethylammonium chloride) monolithic column has been developed for separation and determination of four coumarins (isopimpinelline, bergapten, imperatorin, and osthole) in Fructus cnidii extracts. The effect of polymerization condition including the monomers ratio and the porogens ratio were studied. The mobile-phase composition, such as the composition of organic solvent, the concentration and pH of buffer, was also optimized. Under the same condition (50% ACN and 50% of a 10 mM sodium dihydrogen phosphate electrolyte at pH 4.95), in contrast to 25 min of analysis time in HPLC and 10 min of analysis time in pCEC, a fast separation of these analytes was achieved in less than 5 min in CEC. Method validation was developed in accordance with the analytical procedures. Intra- and interday precisions (RSD) for relative retention time and peak area were less than 1.69 and 4.63%, and LODs were lower than 0.5 microg/mL. Calibration curves of four compounds also showed good linearity (r(2)>0.995). The mean recoveries ranged between 93.91 and 98.65%. With this CEC system, the quality of F. cnidii extracts from various resources was evaluated by determining the contents of the four coumarins.