Development of a Competitive Lateral Flow Assay for Rapid Paraquat Detection

Paraquat dichloride is a widely used herbicide that poses a significant threat to human health. Its prohibition in several countries highlights the need for the development of a highly sensitive device capable of detecting minimum concentrations of this herbicide in food matrices. In this study, we developed a lateral flow test strip using gold nanoparticles conjugated to anti-paraquat antibodies for the visual and quantitative detection of paraquat in food samples. Through the optimization of various critical factors that affect the sensitivity of the test, we achieved visual and quantitative detection limits of 4 ppb and 1.69 ppb, respectively. These values fall below the maximum residue limits allowed for paraquat dichloride in the USA and the European Union. Results can be obtained in as little as 20 min and the test exhibited good repeatability, with a coefficient of variation of 3.27%. There was no cross reaction with the commonly used pesticides chlorpyrifos and glyphosate, indicating good selectivity. The viability of the test was further confirmed through the analysis of real samples such as soybean, potato, and banana, demonstrating its potential as a rapid and sensitive tool for detecting paraquat residues in food samples.