Synthesis and Characterization of Pure Nanoceria for Enhanced Colorimetric Detection of Malathion as a Model Organophosphorus Pesticide

ABSTRACT Organophosphorus pesticides, the largest group of pesticides, when used in excess leaves residues beyond permissible limits on agricultural produce leading to human illness and non‐compliance to safety standards. While existing detection methods are expensive and laborious, simple and cost‐effective nanoparticle based colorimetric detection methods are preferred. In this regard, pure cerium oxide nanoparticles commonly known as nanoceria were synthesized by a facile chemical precipitation method and applied as a sensing material for easy, cost effective, and efficient qualitative and quantitative determination of malathion, used as model organophosphorus pesticide. Nanoceria mediated 3,3’,5,5’ tetramethylbenzidine oxidation enhanced by hydrogen peroxide gets suppressed on addition of the pesticide resulting in visual color difference before and after addition. Pesticide detection efficiency was enhanced through controlled nanoparticle synthesis varying synthesis parameters like type of dispersant reagent, pH of synthesis medium, type of cooling method and time of calcination. Characterization studies were performed on nanoceria before and after pesticide treatment. The developed nanoceria based sensing assay showed linear response as a function of malathion concentration from 0 to 1.0 ppm with a limit of detection ∼ 0.039 ppm. Furthermore, the sensor effectively detected malathion in spiked agricultural samples showing significant potential in food safety monitoring.