The adsorption determination of organophosphate pesticides on microplastics in aquatic and juice samples using a Zr-COF-based magnetic solid-phase extraction

In order to study the adsorption interaction and behavior of organophosphate pesticides (OPPs) on the surface of different microplastics, a Zr-covalent organic framework (COF)-based magnetic solid-phase extraction (MSPE) was established. Due to various interactions (π-π interaction, hydrogen bonding and Zr-O-P coordination interactions), Zr-COF exhibited higher adsorption capacities towards five OPPs than COF without Zr through the theoretical calculation and analysis. The established MSPE-HPLC method showed the detection limit of 0.011–0.019 mg L −1 for OPPs. It was used to determine the adsorption performance of four microplastics towards OPPs. Small sized and aging microplastics showed more adsorption capacities than the large sized and original microplastics. Polylactic acid exhibited higher adsorption capacities than most OPPs, especially with the N element, -NO 2 , and P=O groups, due to the presence of hydrogen bonding. Besides, the method matrix effect was between 2.90%-17.84% in real samples, and the adsorption capacity in juice was significantly higher than that in aquatic samples because of the acidic environment.