High-speed determination of aesculin and aesculetin in Cortex fraxini by micellar electrokinetic chromatography

A new rapid micellar electrokinetic chromatographic (MEKC) method has been developed for the determination of two kinds of coumarin (aesculin and aesculetin) in Cortex fraxini. After a series of optimization experiments, 100 mM boric acid (pH 9.5), 50 mM sodium dodecyl sulfate (SDS), 30 kV applied voltage and 35 degreesC temperature were selected. The contents of aesculin and aesculetin in Cortex fraxini were successfully determined within 6 min by this method with quercetin as internal standard. The relative standard deviations (RSD) of the method are 1.22% for aesculin and 1.02% for aesculetin on the basis of peak areas. The detection limits (3 S/N) are 25 mug mL(-1) for aesculin and 20 mug mL(-1) for aesculetin. Calibration curves are linear in the concentration ranges of 136 - 1020 mug mL(-1) for aesculin (r = 0.9969) and 126 - 945 mug mL(-1) for aesculetin (r = 0.9993), and the recoveries are 98.5% for aesculin and 98.6% for aesculetin.