Monitoring of twenty-two sulfonamides in edible tissues: Investigation of new metabolites and their potential toxicity

The extensive and unregulated use of antibacterial drugs in animal farms in Lebanon can lead to detrimental consequences for the public health. To monitor the levels of sulfonamides and their metabolites in farms in Lebanon, a total of 304 meat samples were collected and analyzed using liquid chromatography coupled to triple quadrupole and hybrid linear ion trap-Orbitrap mass spectrometry following QuEChERS-based extraction. Sulfonamide residues could be detected in forty-six samples, ten of which contained a concentration of sulfaquinoxaline (151.4-1196.7 mu g kg(-1) in chicken samples) and sulfadiazine (109.8 mu g kg(-1) in a beef sample) exceeding the European Union-based maximum residue level by 1-12 folds, and thus were unfit for human consumption. Several acetylated, hydroxylated, and/or sulfated metabolites were identified, some of which were not previously detected in edible tissues. Most identified metabolites exhibited potential toxicity equivalent or higher than that of the parent molecule as estimated by in silica tests. (C) 2015 Published by Elsevier Ltd.