Cholic acid d4

Mass-grade methanol and acetonitrile were from Fisher Chemical (Thermo Fisher Scientific, Boston, MA, USA). Ammonium bicarbonate and formic acid were purchased from Fluka (Dresden, Germany). The ultrapure water was prepared with a Milli Q purification system (Millipore, Burlington, MA, USA). The chemical standards for compound identification were obtained from Sigma-Aldrich (St. Louis, MO, USA), Adamas (Hong Kong, China) or JK Chemical Ltd. (Shanghai, China). The deuterium-labeled internal standards (ISs), including cholic acid-d4,chenodeoxycholic acid-d4, succinic acid-d4,L-leucine-d10, L-phenylalanine-d5, L-tryptophan-d5, L-citrulline-d4, acylcarnitine C10:0-d3 and acylcarnitine C10:0-d3 were from Cambridge Isotope Laboratories, and the natural lipid analogs, including palmitic acid-d3and 1stearic acid-d3,were supplied by Avanti Polar Lipids.

Ammonium acetate, LC-MS-grade formic acid (FA), isopropanol and acetonitrile, and HPLC-grade methanol and methyl tert-butyl ether (MTBE) were purchased from Fisher Scientific (Geel, Belgium). Lipidomics Isotope-labelled internal standards (13 (link)) and Lyso-phosphatidylcholine (LPC) 19:0 (for metabolomics analysis) were purchased from Avanti Polar Lipids (Alabaster, AL, USA). Isotope-labeled internal standards for metabolomics analysis, including tryptophan-d5, valine-d8, phenylalanine-d5, palmitic acid-d3, cholic acid-d4, stearic acid-d3, carnitine C8:0-d3, and carnitine C16:0-d3, were obtained from Cambridge Isotope Laboratories (Tewksbury, MA, USA). Ultrapure water was prepared using the Milli-Q system (Millipore, Billerica, USA).

Formic acid (FA), acetonitrile (ACN), and ammonium acetate (NH4OAc) were obtained from Thermo Fisher, United States. Tryptophan-d5, valine-d8, carnitine C8:0-d3, carnitine C16:0-d3, cholic acid-d4, and stearic acid-d3 (98% purity) were purchased from Cambridge Isotope Laboratories (Tewksbury, MA, United States). Lysophosphatidylcholine LPC (19:0) was obtained from Avanti Polar Lipids (Alabaster, AL, United States). Pure water was purchased from Wahaha ((Hangzhou, China).