Simultaneous LC Analysis of Aloe-Emodin, Rhein, Emodin, and Chrysophanol in Rhizoma Rhei-Type Preparations

A simple and sensitive liquid chromatographic method has been established for simultaneous analysis of four compounds (aloe-emodin, rhein, emodin, and chrysophanol) in Rhizoma Rhei-type preparations. The compounds were separated in less than 20 min on a C18 column with 70:30 methanol–0.2% aqueous acetic acid as mobile phase at a flow rate of 1 mL min−1. The method was validated for specificity, accuracy, precision, and limits of detection. Good linear regression data (r2 > 0.9980) were obtained for all the calibration plots within the ranges tested. The method is an attractive alternative for evaluation of the quality of Rhizoma Rhei-type preparations.