In vivo monitoring of the impact of microplastic particle size on the absorption and transport of Pyrethroids in Malabar spinach.

Microplastics' (MPs) role as pesticide carriers in vegetables remains unclear, particularly regarding size-dependent transport mechanisms. Herein, the fate of eight pyrethroids (PYs) in Malabar spinach was differentially affected by polystyrene microplastics (PS-MPs), as revealed using a novel hollow covalent organic framework-based solid-phase microextraction (HCOF-SPME) technology. This method enabled precise in vivo tracking of pesticide fate while minimizing vegetable sacrifice. Experimental results revealed that PS-MPs enhanced PYs accumulation in roots via adsorption, with smaller MPs (100 nm) exhibiting 1.71-2.52 times higher (500 nm and 1000 nm) vascular transport efficiency to stems compared to larger counterparts, driven by hydrophobic interactions. Notably, PS-MPs co-exposure prolonged PYs persistence, extending maximum half-lives from 4.02 to 12.4 days via carrier-mediated stabilization, thereby increasing residue retention risks during storage and distribution. The developed HCOF-SPME methodology provides a robust analytical platform for investigating multiphase contaminant behavior in aquatic ecosystems, offering actionable insights for food safety assessment and risk management of vegetables in MP-polluted irrigation systems.