Analysis of aesculin and aesculotin in Cortex fraxini by capillary zone electrophoresis

A simple method for quantitative analysis of aesculin and aesculetin in Cortex fraxini was developed using capillary zone electrophoresis (CZE). Berberin was employed as an internal standard, The running buffer was 6 mM Na2B4O7 and 10 mM NaH2PO4 (pH 6.70). The linear calibration range was 32–256 μg ml−1 (r=0.9996) for aesculin and 23–230 μg ml−1 (r=0.9993) for aesculetin. The contents of aeculin and aesculetin in C. fraxini were easily determined within 12 min the pKa values of aesculin and asculetin determined by CZE were 6.56 and 5.62, respectively. A simple method for estimation of the temperature inside the capillary during running was also proposed.