LC/ESI-tandem mass spectrometric determination of bile acid 3-sulfates in human urine: 3β-Sulfooxy-12α-hydroxy-5β-cholanoic acid is an abundant nonamidated sulfate

We developed a highly sensitive and quantitative method to detect bile acid 3-sulfates in human urine employing liquid chromatography/electrospray ionization-tandem mass spectrometry. This method allows simultaneous analysis of bile acid 3-sulfates, including nonamidated, glycine-, and taurine-conjugated bile acids, cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), ursodeoxycholic acid (UDCA), and lithocholic acid (LCA), using selected reaction monitoring (SRM) analysis. The method was applied to analyze bile acid 3-sulfates in human urine from healthy volunteers. The results indicated an unknown compound with the nonamidated common bile acid 3-sulfates on the chromatogram obtained by the selected reaction monitoring analysis. By comparison of the retention behavior and MS/MS spectrum of the unknown peak with the authentic specimen, the unknown compound was identified as 3β,12α-dihydroxy-5β-cholanoic acid 3-sulfate.