Analysis of the major mercapturic acid pathway metabolites of benzo[a]pyrene found in rat urine by nano-electrospray mass spectrometry

Nano-electrospray has been used in combination with high resolution and tandem mass spectrometry in the analysis of the major mercapturic acid pathway metabolites of benzo[a]pyrene (BP). Accurate mass measurements indicate that the [M-H]^- ion of the major metabolite has a chemical formula C₂₅H₂₂NO₆S, which corresponds to the deprotonated form of tetrahydro-trihydroxy-BP-S-N-acetylcysteine. Tandem mass spectrometry of this [M-H]^- ion results in a collision induced dissociation spectrum identical to that of synthetic 7,8,9,10-tetrahydro-8,9,10-trihydroxy-BP-7-S-N-acetylcysteine.