Urea-based magnetic porous organic frameworks as novel adsorbent for the enrichment of phenylurea herbicides in foods

A novel urea-based magnetic porous organic frameworks Fe3O4@UPOFs (ETTA-PPDI) was synthesized by a simple polymerization reaction under mild conditions. The adsorbent displayed desirable adsorption performance for phenylurea herbicides (PUHs) with optimized adsorption time of only 4 min. The adsorption capacities of the adsorbent for PUHs ranged from 47.30 to 111.93 mg g−1. A magnetic solid-phase extraction based on Fe3O4@UPOFs combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established for the efficient determination of six PUHs in food samples (wheat, edible oil and cucumber), with determination coefficient (R2) ≥ 0.9972. The LODs of the method were in the range of 0.003–0.07 μg kg−1 and recoveries ranged from 82.00 to 112.53%. The relative standard deviations were lower than 6.7%. The newly prepared adsorbent displayed great application prospects for the efficient enrichment of trace phenylurea herbicides in complex food matrices.