Electron-capture gas chromatography of methadone after oxidation to benzophenone.
A procedure for the determination of low levels of methadone (6-dimethylamino-4,4-diphenylheptanone-3) in serum has been developed. Methadone is extracted from serum into n-heptane and re-extracted into an acidic aqueous phase. Methadone is oxidized to benzopheone with barium peroxide in sulphuric acid, during which procedure an n-heptane phase is present into which the oxidation product is continuously extracted. The benzophenone formed is determined by means of electron-capture gas chromatography. The recoveries are 100 +/- 3% and 100 +/- 4.5% at the 120 and 16 ng levels, respectively. The minimum amount that can be determined in 1 ml of serum is 4 ng. Interferences from possible metabolies are probably minor. The main cyclic metabolite is only co-determined to a minor extent if the oxidation time is optimized. Comparison of this oxidation method with a combined gas chromatographic-mass spectrometric determination with selected ion monitoring showed identical serum levels.
D001577:Benzophenones / Q000032:analysis*; D002849:Chromatography, Gas; D006801:Humans; D013058:Mass Spectrometry; D008691:Methadone / Q000097:blood*; D010084:Oxidation-Reduction; D012997:Solvents
D001577:Benzophenones; D012997:Solvents; D008691:Methadone