Confirmation of azaperone and its metabolically reduced form, azaperol, in swine liver by gas chromatography/mass spectrometry.

The method described confirms the use of the tranquilizer azaperone by detecting the parent compound and the metabolically reduced form, azaperol. Both are confirmed in swine liver at a target concentration of 10 ppb by gas chromatography/mass spectrometry (GC/MS) with electron ionization in the selected-ion-monitoring mode. Swine liver tissue is ground with dry ice. Acetonitrile is added to extract the drug from the tissue. Sodium chloride buffer is added to the extract in preparation for solid-phase extraction (SPE). The aqueous extract is loaded onto an SPE cartridge designed to extract acidic and neutral drug residues from biological matrixes. The cartridge is washed with methanol and conditioned with sodium phosphate buffer. Azaperone and azaperol residues are eluted with a 2% ammonium hydroxide in ethyl acetate. The extracts are evaporated to dryness under a stream of nitrogen and reconstituted in ethyl acetate for GC/MS analysis. A DB-1 analytical column is used to separate the compounds prior to electron ionization. The parent ion, the base peak ion, and one diagnostic fragment ion are monitored for both compounds. The method was validated with fortified tissue samples containing both azaperone and azaperol. Azaperone-incurred tissues also were analyzed, and the presence of the parent drug and the metabolically reduced form, azaperol, was confirmed.