Methanol, acetonitrile and formic acid were of HPLC-grade and were purchased from TEDIA (Fairfield, USA) and Fisher Scientific (Fair Lawn, NJ). Deionized water was obtained with Wahaha Corporation (Hangzhou, China). 6-Gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8-shogaol, 10-shogaol, zingerone standard compounds were provided by Sichuan Weikeqi Biological Technology Co., Ltd. (Sichuan, China); the purity of each standard was no <98%. All standards were dissolved in 80% methanol based on the concentration of 1?mg/mL and stored at 4?°C.