Transformation of 17a-methyltestosterone in aquatic-sediment systems

Abstract

Two sediment samples that differed with respect to total organic carbon and texture (“sand” and “clay”) were exposed to radio inert 17a-methyltestosterone (MT) or [14C]-radiolabeled 17a-methyltestosterone (14C-MT), under both aerobic and anaerobic conditions, for up to 56 days, to characterize the fate of MT in the aquatic environment. Radio inert MT was quantified by a highly sensitive liquid chromatography/mass spectrometry (LCMS) method and radioactive MT was quantified by HPLC using an in-line flow liquid scintillation counter (LSC). Thedata suggest that MT entering the aquatic environment is converted into metabolites that become tightly associated with the sediment. Half-lives for MT dissipation in the sediment systems ranged from 2-9 days, depending on the sediment type and the presence of oxygen. Sediment type had little effect on MT dissipation. The mineralization of MT under aerobic conditions was low (<9% conversion of MT to CO2).