title: Letter: Methadone N-oxide in the urine of methadone maintenance subjects--an artifact?
mesh_terms: D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D003497:Cyclic N-Oxides / Q000652:urine*; D004355:Drug Stability; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008691:Methadone / Q000652:urine*
chemical_list: D003497:Cyclic N-Oxides; D008691:Methadone