Fabrication of iron oxide@MOF-808 as a sorbent for magnetic solid phase extraction of benzoylurea insecticides in tea beverages and juice samples

A novel magnetic metal organic framework composite (Fe 3 O 4 @MOF-808) was synthesized by a facile solvothermal method and applied as an adsorbent for the magnetic solid phase extraction (MSPE) of benzoylurea insecticides (BUs) from tea beverages and juice samples. The prepared materials were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), vibrating sample magnetometry measurements and N 2 adsorption-desorption experiments. The adsorption (adsorbent amount, extraction time and pH) and elution (elution solvent, elution volume and time) parameters were investigated in detail. Under the optimized experimental conditions, Fe 3 O 4 @MOF-808 exhibited simpler and better reusability than commercial C 18 , with an equivalent adsorption effect. Notably, π-π interactions, hydrophobic interactions and hydrogen bonding interactions contributed to the good adsorption of BUs by Fe 3 O 4 @MOF-808. Finally, a simple and sensitive method was established using Fe 3 O 4 @MOF-808-based MSPE coupled with high-performance liquid chromatography (HPLC). It provided low limits of detection (0.04–0.15 ng/mL), wide linear ranges (0.15–50 ng/mL) and satisfactory recoveries (84.6–98.3%). The proposed method was successfully applied for the fast and sensitive determination of BUs in tea beverages and juice samples.