Ferric oxide/carbon (Fe₂O₃@C) was fabricated via direct carbonization of metal-organic framework of iron (MOF-235) under argon atmosphere. The magnetic Fe₂O₃ nanoparticles are evenly embedded in porous carbon matrix, while original morphology of MOF-235 was well-maintained. The synthesized Fe₂O₃@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 Fe₂O₃@C is a promising adsorbent material for magnetic solid phase extraction of BUs at trace concentrations from tea samples.

氧化铁/碳（Fe ₂ O ₃ @C）是通过在氩气气氛下将铁的金属有机骨架（MOF-235）直接碳化而制得的。磁性Fe ₂ O ₃纳米粒子均匀地嵌入多孔碳基体中，而MOF-235的原始形态得以良好维护。合成的Fe ₂ O ₃@C用作磁性吸附剂，用于萃取五种苯甲酰脲类杀虫剂（BUs）。该材料具有出色的萃取性能，不仅受益于强大的π-π相互作用和疏水相互作用（π-共轭体系），而且还受益于丰富的吸附位点和灵活的传输通道（互连的3D多孔结构）。选择了三因素三级Box-Behnken设计（BBD），以通过响应表面方法优化三个影响很大的参数：吸附剂的量（A），脱附时间（B）和脱附溶剂的体积（C）。建立的与HPLC-UV检测相结合的方法显示出宽线性，范围为0.2–450μg•L ^-1，相对较低的检测下限（0.05–0.10μg•L ^-1），相对标准偏差（RSD）（n  = 7）低于5.47％。此外，该方法成功地应用于茶叶样品中的BUs分析，并研究了不同洗涤方法对茶叶中BUs残留的去除效果。这些结果表明，合成的Fe ₂ O ₃ @C是从茶叶样品中以痕量浓度用于BU的磁性固相萃取的有前途的吸附材料。