Fig. (3) Chromatogram of the rapid assay of cytochrome p450 isoenzymes in BEH C18. Peaks of the major metabolites include 4-acetaminophenol (1), 1-hydroxybufuralol (2), 4-hydroxymephenytoin (3), 7-hydroxycoumarin (4), 4-hydroxytolbutamide (5), 1-hydroxyimidazolam (6)