Spectra grade methanol and acetonitrile were purchased from Tedia (Fairfeild, USA). HPLC-grade formic acid was purchased from Kermel Chemical Reagent Co., Ltd. (Tianjin, China). Purified water was purchased from Wahaha (Zhejiang, Hangzhou, China). The reference standards triptolide, triptonide, triptophenolide, tripterifordin, wilforgine, wilforine, celastrol, demethylzeylasteral, wilforlide A, and pristimerin were purchased from Sichuan Weikeqi Biological Technology Co., Ltd. (Sichuan, China), and their purity was greater than 98%. Commercial Tripterygium glycosides tablets (TGT) were purchased from 13 factories (A-J), three batches of commercial Tripterygium wilfordii tablets (TWT) were from one factory (K), six different batches of commercial Tripterygium hypoglaucum hutch tablets (THHT) were purchased from two factories (L and M).