Improving the detectability of low-abundance p-cresol in biological matrices by chemical derivatization and LC-MS/MS determination.

Gut microbiota produces a wide range of microbial metabolites with potential neuroactive properties. Among these, p-cresol, a by-product of tyrosine breakdown, has gained significant attention in various neuropsychiatric disorders, including autism spectrum disorder. However, current methods fail to detect p-cresol at trace levels in both the systemic circulation and brain, limiting the study of its role in neuropsychiatric disorders.