(Shanghai, China), Rhawn Chemical Technology Co., Ltd. (Shanghai, China), and Shanghai Yuanye Bio-Technology Co. Ltd. (Shanghai, China). Other twenty-eight AA-BA standards (Table , NO. 64-91) were synthesized in our lab according to the previously reported methods . The protocols for the synthesis of these AA-BAs were described in the text of Supporting Information-1, and detailed information of all standards, including full name, abbreviation, CAS number, molecular formula, and molecular weight, was provided in Table . LC-MS grade methanol (MeOH) and acetonitrile (ACN) were supplied by FTSCI Co., Ltd (Wuhan, China). Analytical grade, hydrochloric acid (HCl), sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3), sodium sulfate (Na2SO4), dichloromethane (CH2Cl2), and triethylamine (TEA) were supplied by Aladdin Industrial Co., Ltd (Shanghai, China), for the synthesis of amino acid-conjugated BAs. Stock solutions of all AA-BAs were prepared in ACN at a final concentration of 1 mg/mL for each and stored at -20 °C before use. The water used in the study was purified with a Milli-Q apparatus (Millipore, Bedford, MA). The nylon-66 syringe filters (13 mm, 0.22 μm) were purchased from Jinteng (Tianjin, China).