Development of a deep eutectic solvent-based extraction method for determination of tetracycline, Oxytetracycline and Enrofloxacin residues in cheese sample by high performance liquid chromatography

Excessive use of antibiotics in the animal husbandry causes the accumulation of their residual amounts in food of animal origin such as dairy products. Since the consumption of these foods has a negative effect on human health, authorized organizations such as the European :union: have set maximum residue limits (MRLs) for antibiotics in food of animal origin. This research aimed to present a magnetic ionic solvent based extraction procedure for preparation and preconcentration of tetracycline, oxytetracycline and enrofloxacin residues in cheese samples and their determination by high-performance liquid chromatography equipped with a diode array detector. For this, the effect of various parameters on the extraction efficiency was investigated and optimized. The results showed that the residual amounts of oxytetracycline and tetracycline in 4 and 5 samples of the tested cheeses, respectively, were determined above the permissible limits. Enrofloxacin residue was not found in any of the samples. From the advantages of the proposed extraction method, we can point out the high separation power and the possibility of highly sensitive analyzing of mixed analytes, so that under optimized conditions, the recovery percentage ranges were 80-91. The limits of detection and quantification were respectively less than 1.8 and 6 ng/g, which is much lower than the MRLs set for target antibiotics in cheese (100 ng/g).