Simultaneous determination of anthraquinones in radix Polygoni multiflori by capillary gas chromatography coupled with flame ionization and mass spectrometric detection

A rapid, accurate and reliable analytical method was developed for the simultaneous determination of five major anthraquinones, aloe-emodin, chrysophanol, emodin, physcion, and rhein, in radix Polygoni multiflori, a traditional Chinese herbal medicine. The method comprises a fast ultrasonic extraction with methanol and derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) + 1% trimethylchlorosilane (TMCS) followed by capillary gas chromatographic (GC) separation. The effect of reaction time on the derivatization of anthraquinones was examined. A baseline separation of the anthraquinone and internal standard derivatives was achieved in 15 min. The detection limits range from 0.22 to 0.60 μg/mL for the five anthraquinones. The calibration curves are linear over the concentration range studied (from the detection limits to 40.0 μg/mL) with the squares of correlation coefficients, R2, greater than 0.998. The developed method was successfully applied to the simultaneous determination of anthraquinones in radix P. multiflori samples. The peak identification was confirmed using GC–MS. The contents of anthraquinones in radix P. multiflori samples studied were 27.41, 289.6, 64.22, 202.1, 288.6 μg/g for chrysophanol, emodin, aloe-emodin, physcion, rhein, respectively. All relative standard deviations are less than 3.2%. The recoveries range from 80.2% to 119.3% for the five analytes. To the authors’ best knowledge, this is the first GC method reported for the simultaneous determination of the five anthraquinones in radix P. multiflori.