Flower-like mesoporous Fe3O4@SiO2@F/NiO composites for magnetic solid-phase extraction of imidazole fungicides in tap water, milk and green tea

[Display omitted] •Magnetic fluorine-doped NiO composites Fe3O4@SiO2@F/NiO were prepared as adsorbents.•Flower-like morphology and high specific surface area 187.38 m2·g−1 were presented.•The Ni2+-imidazole and F-F interactions were favorable for the extraction of imidazole fungicides.•The application of the method for tap water, milk and green tea was successful. In this work, magnetic flower-like and fluorine-doped nickel oxide composites Fe3O4@SiO2@F/NiO were prepared and applied for the magnetic solid-phase extraction (MSPE) of five imidazole fungicides. The obtained materials were characterized by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller analysis to verify the successful synthesis. The effect of some experimental parameters on the extraction efficiency were explored to optimize the MSPE conditions, including the adsorbent dosage, ultrasonic time, salt concentration, sample solution pH, elution solvent type and volume. Then, method validation was performed under the optimal conditions in combination with high-performance liquid chromatography-ultraviolet detection. The determination coefficients ranged from 0.9956 to 0.9991, and the limits of detection and limits of quantification for the imidazole fungicides were 0.1–3 μg·L−1 and 0.3–10 μg·L−1, respectively. Moreover, the intra-day and inter-day precisions were evaluated in three different concentrations with relative standard deviations in the range of 1.34 %-13.31 % and 4.96 %-13.92 %. At last, the proposed MSPE method was used to enrich and determine imidazole fungicides in tap water, milk and green tea samples, and the spiked recoveries were in the range of 77.93 %-119.38 %, demonstrating the potential of the method in the determination of imidazole fungicides from real samples.