Simultaneous determination of anthraquinones in rhubarb by high-performance liquid chromatography and capillary electrophoresis.

High-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) were compared to simultaneously determine and separate 11 anthraquinones from rhubarb, including emodin, chrysophanol, rhein and their glucosides, aloe-emodin, sennoside A, and sennoside B. A UV-diode array detector (DAD) at 254 nm with a gradient elution of acetonitrile/water (method A: 0 min 6:94, 12 min 12:88, 15 min 20:80, 40 min 25:75, 53 min 55:45, 55 min 100:0; method B: 0 min 5:95, 2 min 15:85, 5 min 20:80, 12 min 25:75, 15 min 50:50, 19 min 98:2) at 28(+/-1) degrees C (method A) and 30-60 degrees C (method B) in HPLC or with 0.03 M borate buffer (pH 10.0) containing 25% (v/v) acetonitrile with 0.002 M 2,6-di-O-methyl-beta-cyclodextrin (CD) and 0.005 M alpha-CD in CE effectively detected this separation in 25 min. The detection limits of anthraquinones from rhubarb were in the 0.02-0.2 microg/mL and 0.1-0.8 microg/mL ranges for HPLC and CE, respectively. The established HPLC and CE methods are suitable for quantitative determination of emodin, chrysophanol, aloe-emodin, emodin-1-beta-d-glucoside, emodin-8-beta-d-glucoside, chrysophanol-1-beta-d-glucoside, chrysophanol-8-beta-d-glucoside, and rhein-8-beta-d-glucoside.