T ωmca

Cholic acid (CA), chenodeoxy Cholic acid (CDCA), deoxyCholic acid (DCA), lithoCholic acid (LCA), α muriCholic acid (αMCA), βMCA, ωMCA, ursodeoxyCholic acid (UDCA), hyodeoxyCholic acid (HDCA), murideoxyCholic acid (MDCA), taurine conjugated Cholic acid (T-CA), T-CDCA, T-DCA, T-LCA, T- αMCA, T- βMCA, T- ωMCA, T-UDCA, and T-HDCA were purchased from Steraloids (Newport, Rhode Island). T- ωMCA was given by Dr. Daniel Raftery’s laboratory at the University of Washington Northwest Metabolomics Research Center. For internal standards (ISs) , a total of 5 deuterated (d4) ISs were used. Among them the d4-Cholic acid (d4-CA) was purchased from Toronto Research Chemicals Inc (Ontario, Canada), the d4-deoxyCholic acid (d4-DCA) and d4-chenodeoxyCholic acid (d4-CDCA) were purchased from CDN Isotope Inc (Pointe-Claire, Quebec, Canada), the d4-glycine conjugated CDCA (d4-G-CDCA) was purchased from IsoSciences (Ambler, PA), and d4-lithoCholic acid (d4-LCA) was purchased from Steraloids (Newport, Rhode Island). One mg/mL stock solutions of the individual BAs (for standard curve) and IS were prepared in methanol and water (1:1). The 19 individual BA stock solutions were further diluted in 50% methanol to obtain 10 working standard solutions ranging from 0.05 to 10000 ng/mL). The 5 ISs were mixed to obtain a working IS solution in which the concentration of each IS was 10 µmol/mL.