Determination of liquiritin, naringin, hesperidin, thymol, imperatorin, honokiol, isoimperatorin, and magnolol in the traditional Chinese medicinal preparation Huoxiang-zhengqi liquid using high-performance liquid chromatography

High-performance liquid chromatography was employed to determine the contents of the eight marker components liquiritin, naringin, hesperidin, thymol, imperatorin, honokiol, isoimperatorin, and magnolol in the traditional Chinese medicinal preparation Huoxiang-zhengqi liquid. The separation was performed on a C-18 column by stepwise gradient elution with water-methanol-acetonitrile (0.01 min, 68 : 30 : 2; 20 min, 60 : 38 : 2; 50 min, 34 : 64 : 2; 65 min, 34 : 64 : 2; 75 min, 28 : 70 : 2; 85 min, 68 : 30 : 2) as the mobile phase at a flow rate of 1 ml/min, with UV detection at 283 nm. Eight regression equations showed good linear relationships between the peak area ratio of each marker to internal standard and amounts. The recoveries of the markers listed above were 97.4, 98.5, 97.4, 98.6, 97.8, 99.2, 97.0, and 97.5 %, respectively. The repeatability and reproducibility (relative standard deviation) of the method were less than 2.2 and 3.0%, respectively.