Screening of veterinary drug residues in marketed milk and eggs in Oman

Abstract

Background: Residues of veterinary drugs in animal-based food are still under debate. However, they affect human health and are linked to antibiotic resistance. Objectives: The aim of this study was to screen the levels of veterinary drug residues in locally available and imported milk and eggs, and to check if they were within the permitted limits. Methods: Thirty-five compounds from five groups were studied, namely tetracyclines, macrolides, quinolones, sulfonamides, and beta-lactams. The extraction was done using Agilent QuEChERS method, and the extracts were analyzed using liquid chromatography with tandem mass spectrometry. A total of 124 samples of fresh milk and 129 samples of eggs were analyzed. Results: None of the 35 compounds tested were not detected in the samples. Hence, the investigated fresh full-fat milk brands were safe, as no veterinary drug residues were detected in any of the samples. In egg screening, none of the 35 tested antibiotic compounds were not found in Egg-B and Egg-D. Egg-Z was free of 34 antibiotic compounds, but tylosin was detected. Six samples had concentrations ranging from 4.64 to 11.64 μg/kg, and one sample had the highest concentration of tylosin at 89.2 ± 1.19 μg/kg. All these concentrations were below the maximum residue limit. Conclusions: All investigated brands were found to be safe sources of food. Hence, the studied milk and eggs products available in the Omani market are safe to use.