A green ferrofluid based on hydrated deep eutectic solvent for dispersive liquid-liquid microextraction of bisphenols...

In this work, a novel ferrofluid was fabricated by coating Fe₃O₄ nanoparticles with a hydrated deep eutectic solvent synthesized from choline chloride and urea, in which water was rationally introduced to tailor the solvent viscosity and modulate the hydrogen-bonded network. The prepared ferrofluid was used for the dispersive liquid-liquid microextraction of bisphenols in edible oil followed by the determination with high performance liquid chromatography. The integration of the hydrated deep eutectic solvent and Fe₃O₄ nanoparticles enable efficient mass transfer, rapid phase separation, and convenient practical implementation. Molecular dynamics simulation was employed to reveal the underlying extraction mechanism. Under the optimum conditions, excellent performance of linearity ranged from 50 to 5000 μg L^-1 (R² ≥ 0.9990), limit of detection (2.4-4.6 μg L^-1), precision (RSDs ≤5.6%) and extraction recoveries (91.32%-95.91%) were achieved, which suggested a practicable alternative route for the determination of bisphenols in various edible oils.