Mouse fecal samples were prepared as the above protocol. The relative concentrations of the AA-BAs in the samples containing CON feces from 8 mice and CSD feces from 10 mice were analyzed in MRM mode by LC/ESI-QqQ-MS. The LC conditions and the MRM-MS parameters for relative quantification of AA-BAs were the same as above. The peak areas of the detected AA-BAs were automatically generated by MultiQuant software (version 3.0.2, AB Sciex, MA, USA).