Metal-organic frameworks modified melamine foam in pipette-tip for rapid solid-phase extraction of organophosphorus pesticides in fruits and vegetables.

In this work, metal-organic frameworks (MOFs) including Fe-MIL-101 and Ti-MIL-125 were prepared and fixed on the melamine foam (MF) by polyvinylidene fluoride (PVDF) to prepare MF/PVDF/MOFs, which was used as adsorbents in pipette-tip solid-phase extraction (PT-SPE) for rapid extraction of organophosphorus pesticides (OPPs). Then, a gas chromatograph-flame thermionic detector (GC-FTD) was used for simultaneous analysis of Dimethoate (DMT), Iprobenfos (IBF), Parathion-methyl (PAM), and Chlorpyrifos (CPF). The morphology, crystal structure, and functional groups of MF/PVDF/MOFs were characterized, indicating that Ti-MIL-125 and Fe-MIL-101 were successfully synthesized and distributed on MF. The Fe-MIL-101 and Ti-MIL-125 showed good extraction ability for OPPs, which was mainly due to the π-π interaction and the multiple porous structures. Under the optimal conditions, the limit of detection (LODs) of four OPPs was 0.03-0.14 μg L and the RSDs were less than 9.9%. The developed PT-SPE method showed a short extraction time (<3 min). The recoveries in fruits and vegetables (Celery, cabbages, and oranges) ranged from 75.3%-118.8% (RSDs<9.6%). The prepared MF/PVDF/MOFs demonstrated the efficient extraction performance of OPPs, contributing to the rapid pretreatment of OPPs from food and the environment.