Determination of Cryptotanshinone, Tanshinone I, and Tanshinone IIA in Salvia Miltiorrhiza by Micro HPLC with Amperometric Detection

A highly sensitive and simple method for determining cryptotanshinone (Cry), tanshinone I (Tan I), and tanshinone IIA (Tan IIA) in Salvia miltiorrhiza was developed using micro HPLC with electrochemical detection (mu HPLC-ED). The tanshinones were extracted using an ultrasonic method, with methanol as the extractant. The separation was carried out on a C18 (150mmx1.0mm i.d., 3 mu m particle size) analytical column. The mobile phase was acetonitrile-water-formic acid mixture (52:48:0.6, v/v/v) solution. The flow rate and the temperature of the column were set at 30 mu L/min and 35 degrees C. The applied potential was set at 0.4V vs. Ag/AgCl. The peak heights for Cry, Tan I, and Tan IIA were found to be linearly related to the amounts injected, ranging from 0.145 mu mol/L to 3.88 mu mol/L, 0.226 mu mol/L to 3.01 mu mol/L, and 0.149 mu mol/L to 3.98 mu mol/L, respectively. The RSD values of intra-day precision and repeatability were not more than 3.0%, and the recovery of three analytes were ranged from 96.7% to 97.5%. The results of the method validation indicated that this method had good precision and accuracy. As such, the method was applied to analyze crude materials and decoction pieces of Salvia miltiorrhiza.