Facile extraction and determination of organophosphorus pesticides in vegetables via magnetic functionalized covalent organic framework nanocomposites

Facile enrichment and determination of trace organophosphorus pesticides (OPPs) in foods has been a constantly pursuing goal in food safety field. Herein, Zr4+-immobilized covalent organic frameworks (Fe3O4@COF@Zr4+) have been first constructed and utilized as the powerful adsorbents for magnetic solid-phase extraction (MSPE) of OPPs. Owing to the pi-pi stacking interaction, hydrogen bonding and Zr4+-phosphate coordination reaction, the composites exhibited excellent selectivity and superior affinity to OPPs. Under optimized conditions, the proposed MSPE method coupled with GC-FPD showed good linearity (R-2 >= 0.9990) and yielded low limits of detection (0.7-3.0 mu g kg(-1)) for OPPs. Moreover, the developed method was successfully employed for the quantitation of OPPs in spiked vegetable samples and obtained satisfactory recoveries in the range of 87-121% with the relative standard deviations (RSDs) <= 8.9%. These results demonstrated that the prepared nanoparticles hold unique advantages for trace OPPs analysis in foodstuffs.

Automated summary

In this study, Zr4+-immobilized covalent organic frameworks were utilized for magnetic solid-phase extraction of trace organophosphorus pesticides in foods, showing excellent selectivity and affinity for OPPs. The developed method demonstrated good linearity and low limits of detection, and was successfully applied for quantitation of OPPs in vegetable samples with satisfactory recoveries.