Quantitative Determination of Pentazocine in Plasma and of Pentazocine and Metabolites in Urine

GLC methods for the determination of plasma pentazocine and for the determination of urinary pentazocine and its known metabolites are described. The determination of plasma pentazocine involves the extraction of pentazocine and a suitable internal standard, the derivatization of these compounds with heptafluorobutyric acid anhydride, and the chromatography of the derivatives using tritium-foil, electron-capture detection. The determination of urinary pentazocine and two of its metabolites involves the extraction of these compounds and an internal standard, derivatization with a silylating reagent, and the chromatography of the derivatives using flame-ionization detection. The determination of a third urinary metabolite involves adsorption chromatography followed by the same derivatization and chromatographic analysis. The sensitivity and reliability of the techniques are discussed and compared to other methods in the literature.