Analytical methodology for quantification of 15 antiparasitic drugs and their respective metabolites in laying hen eggs was optimized and validated. The method uses acetonitrile as solvent extraction, sodium chloride for salting-out, low-temperature purification and analysis by LC-MS/MS. A total of 348 egg samples were collected in 11 states of Brazil and 50% of the total samples presented antiparasitic residues, which were albendazole, fipronil, fenbendazole, ivermectin, oxibendazole and mebendazole. A total of 12.4% of the samples were considered non-compliant, and residues quantified in these samples were albendazole, fipronil, and mebendazole. Albendazole was always identified as albendazole sulfone. Only one sample presented fipronil and fipronil sulfone; all others exclusively the sulfone metabolite. Fenbendazole was characterized by the presence of both metabolites: sulfone and sulfoxide. Maximum limits adopted are based on the Normative Instruction 51/2019 of the Brazilian Health Regulatory Agency (ANVISA), but albendazole, fipronil, oxibendazole, ivermectin, and mebendazole do not have their maximum residue level established. In addition, metabolites of albendazole, fipronil and fenbendazole in eggs are not considered in this Instruction.
Keywords: LC-MS/MS; antiparasitic; eggs; metabolites; residues.