Methodology for the analysis of benzimidazole anthelmintics as drug residues in animal tissues.

Methodology for the analysis of 8 benzimidazoles as residues in bovine liver is reported. Spiked tissues were extracted by homogenization in saline and ammonium hydroxide and blending with diatomaceous earth. This matrix was packed into a column, and the benzimidazoles were eluted with ethyl acetate. After the sample was further purified, benzimidazoles were separated and quantitated by liquid chromatography with ultraviolet detection (290 nm). Liver tissue samples obtained from cattle which had undergone a drug depletion study of fenbendazole administered per os were analyzed using these methods. The results of these analyses and the application of this approach to multiresidue analysis of drugs in animal tissues are discussed.