Mass spectral characterization of the K-region and non K-region dihydrodiols of 7,12-dimethylbenz (a) anthracene.

Dihydrodiols are derived from intermediary arene oxides during the metabolism of polycyclic aromatic hydrocarbons. In this study, the mass spectra of the trimethylsilyl ether derivatives obtained from the 5,6-dihydrodiol and 8,9-dihydrodiol of 7,12-dimethylbenz [a] anthracene were compared. The mass spectral fragmentation patterns indicate some key features in distinguishing a K-region dihydrodiol from its non K-region isomer. The 8,9-dihydrodiol, a non K-region metabolite, exhibits a greater tendency to undergo a ring contraction fragmentation process while the K-region 5,6-dihydrodiol participates preferably in other fragmentation pathways. The data presented in this report will be useful in charcterizing K-region and nonK-region metabolic epoxidation of polycyclic aromatic hydrocarbons.