Comparative study on the derivatization of l-α-acetylmethadol metabolites for electron capture gas-liquid chromatography

Six reagents-trichloroacetyl chloride, trichloroacetic anhydride, pentafluorobenzoyl chloride, heptafluorobutyryl chloride, heptafluorobutyric anhydride, and trifluoroacetic anhydride-were evaluated as potential derivatizing reagents for quantitating the metabolites of l-α-acetylmethadol (LAAM)-noracetylmethadol, dinoracetylmethadol, methadol, and normethadol-by electron capture gas-liquid chromatography. All of the reagents studied reacted quantitatively with all of the metabolites except methadol; however, trichloroacetyl chloride was found to be the most satisfactory general reagent for analyzing these metabolites in biological fluids. A gas-liquid chromatographic method is presented which combines both flame ionization and electron capture detection for quantitating plasma and urine levels of methadone, l-α-acetylmethadol and its metabolites.