Development of a new dispersive liquid-liquid microextraction/UPLC method for determining bisphenols and estrogens in...

This study presented a new method of dispersive liquid-liquid microextraction based on Fe₃O₄ nanoparticles-enhanced hydrophobic magnetic deep eutectic solvent (NPE-MDES-DLLME) for the simultaneous enrichment of six estrogens and bisphenols in water samples. The enriched analytes were then detected by ultra-performance liquid chromatography-fluorescence detection (UPLC-FLD). The innovations of the proposed method lie in two aspects: synthesis of a new hydrophobic MDES extractant composed of bis(2-ethylhexyl) phosphate, 1-hexanol, and nickel chloride, and addition of Fe₃O₄ nanoparticles to enhance the extraction efficiency as well as speed up phase separation. Key parameters affecting extraction efficiency, including MDES composition, sample volume, extraction time, and elution conditions, were systematically optimized. Consequently, the method exhibited excellent analytical performance, characterized by good linearity (0.070-500 µg·L^-1, R² > 0.99), high enrichment factors (543-640), and low limits of detection (0.021-0.096 µg·L^-1). When applied to real water samples, the proposed method yielded spiked recoveries ranging from 90.1% to 112.0% with relative standard deviations (RSDs) below 8.0%. Furthermore, greenness assessments using the ComplexAPI and AGREE metrics confirmed the method's eco-friendliness. The developed NPE-MDES-DLLME/UPLC-FLD method provided a reliable, sensitive, and cost-effective approach for determining ultra-trace levels of estrogenic and bisphenol pollutants in the aquatic environment.