All the medicinal materials were tested, and their quality met the relevant standards of the 2020 edition of the Chinese Pharmacopoeia. Standard reference compounds, including epiberberine (wkq20031807), coptisine (wkq20021306), palmatine (wkq20051201), berberine (wkq20032408), baicalin (wkq20010908), wogonoside (wkq20040108), baicalein (wkq20022608), wogonin (20030204), rhein (wkq20052209), aloe-emodin (wkq20032708), emodin (wkq20041308), chrysophanol (wkq20081705), and physcion (wkq20040101) were purchased from Weikeqi Biotechnology Co., Ltd (Chengdu, China). The purity of all standard products was higher than 98%. Chromatographic grade acetonitrile and formic acid were purchased from Thermo-Fisher (US). |