Synthesis of magnetic metal-organic framework composites, Fe3O4-NH2@MOF-235, for the magnetic solid-phase extraction of benzoylurea insecticides from honey, fruit juice and tap water samples

Herein, a novel, fusiform-like magnetic metal-organic framework material (Fe3O4-NH2@MOF-235) was fabricated by a facile two-step solvothermal approach. Then, Fe3O4-NH2@MOF-235 was applied as an adsorbent in magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography (HPLC) for the simultaneous extraction and determination of five kinds of benzoylurea insecticides (flufenoxuron, chlorbenzuron, teflubenzuron, diflubenzuron and triflumuron) from honey, fruit juice and tap water samples. Moreover, potential variables influencing the MSPE efficiency were optimized. Under the optimized conditions, an excellent linearity was achieved in the range of 1.0-300.0 mu g L-1 for teflubenzuron and flufenoxuron and 2.0-300.0 mu g L-1 for diflubenzuron, chlorbenzuron and triflumuron, with the correlation coefficients of 0.9991-0.9995. The limits of detection for the analytes were 0.25-0.5 mu g L-1, and the recoveries at three fortified concentration levels ranged from 76.45% to 90.74% for the honey samples, 79.95-95.27% for the fruit juice samples, and 84.02-99.62% for the tap water samples. The pi-pi stacking and hydrophobic interactions between Fe3O4-NH2@MOF-235 and the analytes played an important role in the adsorption process. Moreover, maximum adsorption could be achieved within 5 minutes with very little adsorbent for all the samples. Therefore, the magnetic Fe3O4-NH2@MOF-235 composite combined with MSPE is a convenient approach to detect benzoylurea insecticides in actual samples.