32P-Postlabeled Adducts. Incubations contained 0.06 mM N-OH-MeIQx or N-NO-MeIQx, 3 mM 2′-deoxyguanosine 3′-monophosphate, 0.1 mM DETAPAC, 100 mM potassium phosphate buffer. N-OH-MeIQx was incubated at pH 7.4. N-NO-MeIQx was incubated in the absence and presence of 0.1 mM HOCl (pH 5.5). Liver DNA was from a mouse administered 20 mg/kg MeIQx by gavage for 10 successive days. Exposure times were 15 min for N-OH-MeIQx, 6 hrs for N-NO-MeIQx, 1 hour for N-NO-MeIQx/HOCl, and 16 hrs for liver DNA.