Determination of active anthraquinones in Rheum and its tea preparations by micellar electrokinetic capillary electrophoresis

Abstract

Objective: To establish an instant determination method of emodin, aloe-emodin and rhein, from Rheum, and one of their preparations, Qinghai Wild Dahuang Tea, by micellar electrokinetic capillary electrophoresis for the first time. Method: Separation was carried out in an uncoated fused silica capillary (75 μm x 50.0 cm). Meanwhile, a running voltage 20 kV, 15.0 mmol·L-1 borax buffer with 30.0 mmol·L-1 SDS and 10% ethanol (pH 9.60) and a UV detector at 254 nm were adopted. Result: The linear calibration rang was 4-120 mg·L-1 (r = 0.992 1) for emodin, 10-200 mg·L-1 (r = 0.997 0) for aloe-emodin, and 2-100 mg·L-1 (r = 0.997 1) for rhein, respectively. Under the optimum conditions, the relative standard deviation (RSD) values (n = 6) for the migration time and the peak area of each peak were 0.59%-0.80%, 1.30%-3.22%, respectively. The contents of the analytes were easily determined with recoveries ranging from 97.6%-102.3%. Conclusion: The method is proved to be simple, rapid and accurate, and can be used for the quality control of medicinal herb, Rheum, and its tea preparation.