VOLUME 19 NUMBER 1 (January to June 2026)

Development of Quercetin-modified silver nanoparticles for paper-based detection of methomyl pesticide

Carbamates are among the widely used agrochemicals due to their broad spectrum of activity, high pesticide efficiency, and relatively lower environmental half-life. Although they offer several agricultural benefits, post-harvest carbamate residues in fruits and vegetables pose significant health risks. Traditional methods such as chromatography and enzyme inhibition assays are well-established for the detection of pesticides. However, these methods tend to be resource-intensive, often requiring sophisticated equipment and advanced technical expertise, which can limit their applicability in routine agricultural settings when quick testing is essential. In this study, a paper-based colorimetric device was developed by impregnating quercetin-modified Silver nanoparticles (Q-AgNPs) onto a paper substrate for the detection of the carbamate pesticide, methomyl. The optimum pH of the test solutions was found to be 7.43-8.00, while the optimum dipping time is 60 s and the optimum drying time is up to 120 min. Digital images of the developed strips were captured using a high-resolution scanner and analyzed through ImageJ software, providing a semi-quantitative measurement of methomyl concentration in the samples. The detection limit was found to be 2.621 mg/L, with a limit of quantification (LOQ) of 7.943 mg/L. Additionally, the percent recovery of the spiked samples was estimated to be 93 to 95%, further verifying the efficiency of the sensor in detecting methomyl residues. Furthermore, the concentrations detected by the paper-based device were verified by UV-Vis spectrophotometry, supporting its potential as a screening tool for semi-quantitative on-site pesticide residue analysis, promoting safer agricultural practices and consumer health protection.