UC Davis

Herein, a novel method, magnetic effervescent tablet-assisted ionic liquid-based dispersive liquid-liquid microextraction (META-IL-DLLME), was pioneered for extraction and preconcentration of polybrominated diphenyl ethers (PBDEs) in liquid matrix samples. In this proposed method, a magnetic effervescent tablet, containing CO₂ sources, ionic liquids and Fe₃S₄ magnetic nanoparticles (MNPs), combines extractant dispersion and magnetic recovery into one-step. Fe₃S₄ was synthesized, characterized and applied it for the first time to the newly developed method, and its extraction recoveries (ERs) for PBDEs were 20.8-32.0% higher than those of conventional Fe₃O₄ MNPs. The increased ERs of Fe₃S₄ resulted from its larger specific surface area and pore size. Some important parameters were rigorously optimized, such as kinds of magnetic nanoparticles, effervescent agents, extraction solvents and their volumes, elution solvents, extraction temperature and salt addition. Under the optimized conditions, the META-IL-DLLME method combined with HPLC-DAD analysis gave the linear ranges of 0.1-0.5-100 µg L^-1 with correlation coefficients of > 0.9990. The ERs ranged from 80.7% to 99.3%, and the limits of detection and quantitation were 0.012-0.078 µg L^-1 and 0.04-0.26 µg L^-1, respectively. The intra- and inter-day precisions, expressed as relative standard deviations (RSD, n = 6), were 1.32-4.83% and 1.99-4.25%, respectively. To evaluate its matrix effect, the relative recoveries of PBDEs from tap and river water, skim and whole milk, pregnant women and women serum samples at three fortification levels (2.0, 5.0 and 20.0 µg L^-1) were in the range of 77.3-106.7%. Overall, the commercial Fe₃O₄ MNPs can only be used for magnetic separation in microextraction procedures, while Fe₃S₄ MNPs gave the higher adsorption and extraction efficiency for organic analytes besides the convenient magnetic separation. Therefore, the results obtained in this study provide a superior alternative for the conventional magnetic separation and adsorbent material. Also, this newly developed method has a great potential in routine monitoring of liquid matrix samples.