Salt-enhanced natural deep eutectic solvent microextraction: Eco-friendly tilmicosin detection in food

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A fast and eco-friendly salt-assisted dispersive liquid–liquid microextraction (SADLLME) method was developed for separation and preconcentration of tilmicosin (TLM) from complex food matrices prior to HPLC-DAD analysis. This is the first report for the efficient extraction of TLM from milk and chicken meat utilizing a tailor-made hydrophobic natural deep eutectic solvent (NADES), composed of DL-menthol and oleic acid. The method introduces a green alternative to the reported TLM extraction methods, which rely on hazardous organic solvents and labor-intensive procedures. Key experimental parameters, including NADES composition and volume, salt type and concentration, and pH, were systematically optimized to achieve maximum performance. Under optimal conditions, the method demonstrated high sensitivity with LOD and LOQ values of 0.22 and 0.67 µg/mL, respectively, and an outstanding extraction efficiency of 99% with %RSD values below 2%. Recovery tests confirmed the method’s accuracy and reliability. Environmental sustainability was quantitatively assessed using AGREEprep and SPMS tools, both of which validated the method’s green credentials. This work aligns with green analytical chemistry principles and offers a practical solution for monitoring veterinary drug residues in food.