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 product produced by the soil microorganism Streptomyces avermitilis. Ivermectin is a unique hydrogenation product of abamectin. A sensitive HPLC-fluorescence method was developed to determine abamectin or ivermectin 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 validated was from 2 ppb to 2 ppm (microgram/g) with average recoveries of 84% for both abamectin and ivermectin. Abamectin and ivermectin can be analyzed simultaneously because the fluorescent derivatives of the two compounds are chromatographically well resolved on the C18 column used. The method was developed to support studies concerning the dissipation of incurred abamectin or ivermectin residues in cattle feces postdose and postdeposition