Identification of metahydroxyamphetamine as a metabolite of amphetamine in the rat

m-Hydroxyamphetamine (mOHA) was found as a metabolite of amphetamine in rat urine, liver perfusate and bile. The identity was established with a gas chromatograph-mass spectrometer (GC/MS) by its retention time, mass spectrum and selective-ion-monitoring of fragments representing both the side chain and the aromatic moiety. Furthermore, deuterium-labelled amphetamine was used in order to circumvent the possibility of interference by substances with similar structure of endogenous or exogenous origin. The amount of mOHA was low, about 10% of the ring hydroxylation could be accounted for as metahydroxylation.