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 exhib-
ited 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 de-
sign (BBD) was selected to optimize three greatly influential parameters: amount of adsorbent (A), des-
orption 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 , rela-
tively 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.