Combination of dispersive solid phase extraction using Fe₂O3@ZIF-8@CeO₂ nanocomposite and dispersive liquid–liquid microextraction as an efficient sample preparation method for the extraction of heavy metal ions from honey

A Fe₂O 3 @ZIF-8@CeO₂ core–shell nanocomposite was reported as a highly effective sorbent for the dispersive solid phase extraction of Pb(II), Cd(II), and Cu(II) ions from honey. The combination of porous ZIF-8 network with Fe and CeO₂ resulted in a high density of accessible sites, providing strong affinity toward heavy metal ions. The successful formation and well-defined morphology of the composite were confirmed by XRD, FT-IR, and SEM analyses. The sorbent was applied in a combined dispersive solid-phase extraction and dispersive liquid-liquid microextraction approach for efficient extraction and preconcentration of the target metal ions. Acetonitrile was used as the desorption solvent, and 1,1,2,2-tetrachloroethane served as the extraction solvent. Quantification of the enriched analytes was performed by flame atomic absorption spectrometry. Critical parameters, including sorbent amount, vortexing time, pH, type and volume of extraction and desorption solvents, and salt addition were systematically optimized to achieve maximum extraction efficiency. Under the optimized conditions, the proposed method showed high extraction efficiencies, with extraction recoveries of 97.5, 95.8, and 92.4% for Cu(II), Cd(II), and Pb(II) ions, respectively. The method provided low detection limits of 0.18, 0.27, and 0.50 µg kg⁻¹ for Cu(II), Cd(II), and Pb(II) ions, while intra- and inter-day relative standard deviations were in the ranges of 2.8–3.9% and 3.2–4.5%, respectively. Application to honey samples resulted in relative recoveries ranging from 88.9 to 97.4%, demonstrating satisfactory accuracy in the presence of the complex honey matrix. The sorbent also showed good reusability, maintaining its extraction performance over seven consecutive cycles with less than 5% decrease in extraction recoveries. The method was successfully applied to a variety of honey samples, demonstrating the robustness and sensitivity of the approach, as well as the strong potential of the Fe₂O 3 @ZIF-8@CeO ₂ sorbent for practical monitoring of heavy metal ions in complex food matrices.