Hydrophobic deep eutectic solvent based ferrofluid for vortex-assisted liquid-liquid microextraction of bisphenol A and alkylphenols from water and beverages samples

A novel ferrofluid comprising of Fe 3 O 4 , chitosan and hydrophobic deep eutectic solvent formed from benzyltriethylammonium chloride and caprylic acid was developed and applied as green microextraction medium in vortex assisted liquid-liquid microextraction (VA-LLME) for bisphenol A and alkylphenols in water and beverage samples. The ferrofluid’s structural and magnetic were confirmed via Fourier transform-infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Extraction conditions were systematically optimized using a single factor optimization and central composite design, achieving limits of detection of 0.03-0.05 μg L - ¹ and quantification of 0.1-0.2 μg L -1 , with intra- and inter-day precisions ≤1.9% and ≤2.1%, respectively. After the VA-LLME process, the phase separation can be completed quickly with the help of magnet, without requiring special equipment and complex operations, reducing sample preparation time to under 3 min and enhancing extraction efficiency. The microextraction mechanism was further investigated using density functional theory. Subsequently, combined with high-performance liquid chromatography-fluorescence detector, this method was applied for quantitatively determination of bisphenol A and alkylphenols in water and beverage samples, with spiked recoveries of 97.8-106.3%. The approach combines operational simplicity, rapidity, low cost, and environmental compatibility, highlighting its potential for routine applications in food safety and environmental monitoring.