DETERMINATION OF ABAMECTIN AND OR IVERMECTIN IN CATTLE FECES AT LOW PARTS-PER-BILLION LEVELS USING HPLC WITH FLUORESCENCE DETECTION/

Abamectin and ivermectin are potent antiparasitic animal health drugs that differ structurally by a double bond. Abamectin is a natural prod uct produced by the soil microorganism Streptomyces avermitilis. Iverm ectin is a unique hydrogenation product of abamectin. A sensitive HPLC -fluorescence method was developed to determine abamectin or ivermecti n residues in bovine feces. The limit of quantitation is 2 ppb (ng/g) and the limit of detection is 1 ppb (wet weight basis). The range vali dated was from 2 ppb to 2 ppm (mu g/g) with average recoveries of 84% for both abamectin and ivermectin. Abamectin and ivermectin can be ana lyzed simultaneously because the fluorescent derivatives of the two co mpounds are chromatographically well resolved on the C-18 column used. The method was developed to support studies concerning the dissipatio n of incurred abamectin or ivermectin residues in cattle feces postdos e and postdeposition.