Identification of 2,5-dimethoxy-4-ethylthiophenethylamine and its metabolites in the urine of rats by gas chromatography–mass spectrometry

A simple and specific method based on gas chromatography–selected ion monitoring-mass spectrometry (GC–SIM-MS) for the analysis of in vivo metabolism of 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2) in rats is described. Three male rats were administered 20 mg/kg of 2C-T-2 by intra-peritoneal injection, and 24 h urine fractions were collected before and after the administration for analysis. After acidic hydrolysis of the urine samples, the metabolites were liquid–liquid extraction and analyzed by a quadruple mass spectrometer in the selected ion monitoring mode. The findings show that four metabolites of 2-(4-ethylthio-2,5-dimethoxyphenyl)-ethanol (Mw: 242), 4-ethylthio-2,5-dimethoxyphenyl acetic acid (Mw: 256), 1-acetoamino-2-(2-hydroxy-4-ethylthio-5-methoxyphenyl)-ethane (Mw: 269) and 1-acetoamino-2-(2-methoxy-4-ethylthio-5-hydroxyphenyl)-ethane (Mw: 269) are present and the metabolic pathway for 2C-T-2 in the rat is proposed.