Determination of Benzimidazole Residues in Edible Animal Food by Polymer Monolith Microextraction Combined with Liquid Chromatography−Mass Spectrometry

A sensitive method has been developed for the simultaneous determination of 10 benzimidazole residues and some of their metabolites in egg, milk, chicken, and pork. This method is based on the combination of polymer monolith microextraction (PMME) technique with liquid chromatography and electrospray ionization mass spectrometry (LC-ESI/MS). The extraction was performed with a poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EGDMA) monolithic capillary column. Under the optimized extraction conditions, good extraction efficiencies for the targets were obtained with no matrix interference in the subsequent detection. The LODs (S/N = 3) for 10 benzimidazoles were found to be 0.56−2.76 ng g−1 in egg, 0.50−1.41 ng mL−1 in milk, 0.09−0.28 ng g−1 in chicken, and 0.08−0.15 ng g−1 in pork. The recoveries in egg, milk, chicken, and pork matrices ranged from 75.2 to 116.8% spiked at different levels with analytes, with RSDs of <13.7%. The method was later successfully applied for the determination of primary and metabolite residues in eggs after oral administration of albendazole to hens.