OBJECTIVETo 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.

METHODSeparation was carried out in an uncoated fused silica capillary (75 microm x 50.0 cm). Meanwhile, a running voltage 20 kV, 15.0 mmol x L(-1) borax buffer with 30.0 mmol x L(-1) SDS and 10% ethanol (pH 9.60) and a UV detector at 254 nm were adopted.

RESULTThe linear calibration rang was 4-120 mg x L(-1) (r = 0.992 1) for emodin, 10-200 mg x L(-1) (r = 0.997 0) for aloe-emodin, and 2-100 mg x 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%.

CONCLUSIONThe 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.