Rapid determination of multiclass antibiotics and their metabolites in milk using ionic liquid-modified magnetic chitosan nanoparticles followed by UPLC-MS/MS

This research introduced a rapid and efficient method for simultaneous pre-concentration and determination of twenty-two antibiotics and their metabolites in milk samples using functional imidazole-based ionic liquid -modified magnetic chitosan nanoparticles followed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Different techniques characterized the synthesized nanoparticles. Experimental variables were studied and optimized by the one-factor-at-a-time approach and Box-Behnken design. All anti-biotics showed good linearity, with correlation coefficients of more than 0.995. The matrix effects were greatly minimized using the proposed method. The range of average recoveries was from 85.9 to 107.5%, and precision values were presented as RSDs, which were below 9.2%. The limits of detection were 0.04-0.19 mu g kg-1. The measurement uncertainty was estimated by the bottom-up approach. The conformity method was applied in the analysis of real milk samples. Antibiotic residues were found in 124 samples out of 241 milk samples. Never-theless, it was found that 24 of 133 raw cow milk samples and 15 of 108 pasteurized milk samples were above maximum residue limits. Finally, the potential human health risk estimated using the hazard quotient approach, based on the estimated daily intake and acceptable daily intake, showed a negligible risk for human health from milk consumption.