DETERMINATION OF LEVAMISOLE IN ANIMAL-TISSUES USING LIQUID-CHROMATOGRAPHY THERMOSPRAY MASS-SPECTROMETRY

A method is described for the determination of the anthelmintic levami sole in liver, kidney and muscle using liquid chromatography-thermospr ay mass spectrometry. Samples are extracted by homogenizing with ethyl acetate, applied to Bakerbond CN solid-phase extraction columns, wash ed pith chloroform-hexane and eluted with methanol. The extracts are e vaporated to dryness under nitrogen and the residues are dissolved in mobile phase and injected into the LC-MS system. The positive M + 1 io n at m/z 205 is monitored. The detection limit for the assay is 5 ng g (-1). Mean recoveries were about 93% for liver, 85% for kidney and 79% for muscle. The assay has been used for statutory testing purposes an d for measuring levamisole concentrations in liver,kidney and muscle f rom sheep dosed with a commercial drench containing levamisole.