Metal-organic frameworks derived magnetic porous carbon for magnetic solid phase extraction of benzoylurea insecticides from tea sample by Box-Behnken statistical design.

• A novel Fe 2 O 3 @C was synthesized by carbonizing MOF-235 under Ar atmosphere. • The magnetic Fe 2 O 3 particles were evenly embedded in porous carbon matrix. • The Fe 2 O 3 @C was used to extract benzoylurea insecticides from tea drink samples. • This work studied the removal effect of three washing on residues from tea leaf. • This method showed satisfactory recovery, wide linear range and low LODs. Ferric oxide/carbon (Fe 2 O 3 @C) was fabricated via direct carbonization of metal-organic framework of iron (MOF-235) under argon atmosphere. The magnetic Fe 2 O 3 nanoparticles are evenly embedded in porous carbon matrix, while original morphology of MOF-235 was well-maintained. The synthesized Fe 2 O 3 @C was used as magnetic sorbent for extracting five benzoylurea insecticides (BUs). The materials exhibited excellent extraction performance, which benefited not only from the strong π-π interaction and hydrophobic interaction (π-conjugated system), but also to the abundant adsorption sites and flexible transport channel (the interconnected 3D porous structure). A three-factor-three-level Box-Behnken design (BBD) was selected to optimize three greatly influential parameters: amount of adsorbent (A), desorption time (B) and volume of desorption solvent (C) by response surface methodology. The established method coupled to HPLC-UV detection showed wide linearity with the range of 0.2–450 μg•L−1, relatively low limits of detection (0.05–0.10 μg•L−1) with the relative standard deviation (RSD) (n = 7) lower t than 5.47%. Moreover, the proposed method was successfully applied to analyze BUs in tea samples and investigate the removal effect of different washing on BUs residues from tea leaf. These results indicated that the synthesized Fe 2 O 3 @C is a promising adsorbent material for magnetic solid phase extraction of BUs at trace concentrations from tea samples. [ABSTRACT FROM AUTHOR]