Background: The widespread use of tetracyclines (TCs) raises environmental concerns due to their persistence. Traditional extraction methods suffer from toxic solvents and operational complexity, demanding green alternatives. The use of magnetic ionic liquids (MILs) in aqueous biphasic systems (ABS) offers high extraction efficiency and facilitates phase separation through magnetic responsiveness, providing a simpler and potentially more effective alternative to conventional solvent extraction methods.
Results: Four geminal dicationic magnetic ionic liquids (GDMILs) functionalized with heterocycles and magnetic radicals were tailored for efficient tetracyclines (TCs) extraction via ABS. The GDMIL-ABS achieved >98 % extraction efficiency within 5 min under solvent-free conditions, and allowed rapid magnetic separation with good recyclability over five cycles. Phase behavior was influenced by GDMIL structure, temperature, and salt type. The method showed excellent recoveries (98-103 %) and satisfactory sensitivity with limits of detection (LOD) and quantitation (LOQ) in the ranges of 3.441-5.231 and 11.47-17.42 μg/L, respectively. Real environmental sample analysis confirmed high accuracy (92-98 %) and enrichment factors (112-229). Density functional theory (DFT) calculations revealed that extraction performance was primarily governed by TC-GDMIL binding energy and salting-out effect.
Significance: The developed GDMIL forms magnetically responsive ABS with strong extraction capacity and sensitivity for TCs. The interaction mechanisms between the GDMIL and TCs were elucidated, providing valuable insights for the development of multifunctional ILs. The proposed GDMIL-based ABS provides a rapid, effective, and sensitive approach for detecting antibiotics in aqueous environments.
Keywords: Aqueous biphasic system; DFT calculations; Extraction; Magnetic ionic liquids; Tetracyclines.
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