MONOCLONAL-ANTIBODY FOR MULTIRESIDUE ELISA OF BENZIMIDAZOLE ANTHELMINTICS IN LIVER

A monoclonal antibody has been prepared that binds the major benzimidazole anthelmintic drugs, including albendazole, fenbendazole, oxfendazole, and several of their metabolites. In addition, the antibody binds methyl benzimidazolecarbamate, a metabolite and breakdown product of the pesticide benomyl. The antibody was elicited from mice using the novel hapten methyl 5 (6)-[(carboxypentyl)-thio]-2-benzimidazolecarbamate and was used to develop an ELISA method that can detect multiple benzimidazole drug and pesticide residues at concentrations between 1 and 8 ppb. The ELISA provided the basis for quantification of drug residues in bovine liver using aqueous extraction. The sulfoxide and sulfone metabolites of albendazole and fenbendazole were readily extractable and quantifiable by this method. ELISA of liver tissue from cows treated with fenbendazole produced excellent agreement with the results of HPLC analysis. In bovine liver samples fortified with equal amounts of benzimidazole drug and sulfoxide and sulfone metabolites, the limits of detection were 58 ppb for the albendazole group and 120 ppb for the fenbendazole compounds. This sensitivity enables rapid identification of samples requiring residue-specific quantitative analysis. Since the ELISA method employs stable nonhazardous materials and reagents, it could be performed in the field for rapid screening of meat products for undesired residues.