Analysis of veterinary drug residues in cheese by ultra‐high‐performance LC coupled to triple quadrupole MS/MS

A simple, reliable, and fast multiresidue method has been developed for the determination of 17 veterinary drugs belonging to several families (macrolides, sulfonamides, and anthelmintics) in cheese at trace levels. Ultra‐high‐performance LC coupled to MS/MS has been used for the analysis of these compounds in less than 9 min. Veterinary drug residues have been extracted from cheese samples using a QuEChERS (quick, easy, cheap, effective, rugged, and safe)‐based extraction procedure without applying any further clean‐up step. Matrix‐matched calibration was used for quantification and recoveries were calculated at three concentration levels (10, 50, and 100 μg/kg). The obtained values ranged from 70 to 110% for the selected compounds except for tylosin and josamycin at 100 μg/kg (111.7 and 112.7%, respectively). Intra‐ and interday precision were also evaluated and RSDs were lower than 25% in all the cases. LOQs ranged from 0.3 μg/kg (for thiabendazole, oxfendazole, mebendazole, josamycin, and fenbendazole) to 10.5 μg/kg (abamectin), whereas decision limit and detection capability ranged from 2.3 (thiabendazole) to 11.3 (abamectin) and 4.2 (thiabendazole) to 14.3 μg/kg (abamectin), respectively. Finally, 13 samples were analyzed and traces of thiabendazole were detected in two different cheeses.