Gas chromatographic and mass fragmentographic assays of carcinogenic polycyclic hydrocarbon epoxide hydratase activity.

A specific and very sensitive procedure for the determination of epoxide hydratase activity in hepatic microsomes is described. Any polycyclic hydrocarbon epoxide can be used as a substrate; in this study, benzo(a)anthracene-5,6-oxide, benzo(a)pyrene-4,5-oxide and 3-methylcholanthrene-11,12-oxide were utilized. The corresponding trans-diols formed during incubation are separated and evaluated using either an electron-capture gas chromatographic method for the determination of their chloromethyldimethylsilylated derivatives or gas chromatographic-mass fragmentographic measurement of their trimethylsilylated derivatives. Concentrations as low as 1 ng per millilitre of incubation mixture can be estimated.