A functionalized magnetic covalent organic framework containing the nitro groups (Fe3O4@COF-(NO2)2) with core-shell structure was synthesized for magnetic solid phase extraction (MSPE) of six neonicotinoid insecticides residue in vegetable samples. The structure of Fe3O4@COF-(NO2)2 was investigated by various characterization techniques. The Fe3O4@COF-(NO2)2 exhibits the excellent thermal and chemical stability, high surface area (254.72 m2 g-1), total pore volume (0.19 cm3 g-1), high magnetic responsivity (27.7 emu g-1), which can be used as an ideal adsorbent for rapid isolation and enrichment of target analytes. A sensitive method was developed by using Fe3O4@COF-(NO2)2-based MSPE coupled with HPLC with UV detection. It offered good linearity within the range of 0.1-30 ng mL-1, low limits of detection (S/N = 3) of 0.02-0.05 ng mL-1. Furthermore, high enrichment factors of 170-250 for six neonicotinoid insecticides were obtained. The applicability of Fe3O4@COF-(NO2)2 is demonstrated for measuring trace neonicotinoid residues in vegetable samples with satisfactory recoveries, which ranged from 77.5 to 110.2%. The results indicated that the Fe3O4@COF-(NO2)2 microspheres offer great potential for efficient extraction of neonicotinoid insecticides from complex samples.

中文翻译：

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一种功能化的磁性共价有机框架，用于灵敏测定蔬菜样品中的微量新烟碱残留。

合成了具有硝基-Fe3O4 @ COF-（NO2）2核-壳结构的功能化磁性共价有机骨架，用于磁性固相萃取（MSPE）蔬菜样品中的六种新烟碱类农药残留。通过各种表征技术研究了Fe3O4 @ COF-（NO2）2的结构。Fe3O4 @ COF-（NO2）2具有优异的热稳定性和化学稳定性，高表面积（254.72 m2 g-1），总孔体积（0.19 cm3 g-1），高磁响应率（27.7 emu g-1），可以用作快速分离和富集目标分析物的理想吸附剂。通过使用基于Fe3O4 @ COF-（NO2）2的MSPE结合HPLC和UV检测，开发了一种灵敏的方法。它在0.1-30 ng mL-1的范围内提供了良好的线性，检测限（S / N = 3）的下限为0.02-0.05 ng mL-1。此外，获得了六种新烟碱类杀虫剂的170-250的高富集因子。证明了Fe3O4 @ COF-（NO2）2的适用性用于测量蔬菜样品中的痕量新烟碱残留，回收率令人满意，为77.5至110.2％。结果表明，Fe3O4 @ COF-（NO2）2微球为从复杂样品中有效提取新烟碱类杀虫剂提供了巨大潜力。