Development of a Low-Cost Colorimetric Assay for Rapid Detection of Pesticide Residues in Agricultural Samples

Pesticide contamination in agricultural products poses serious risks to environmental safety and human health, particularly in developing regions where access to advanced analytical instruments is limited. The present study reports the development of a simple, low-cost, and rapid colorimetric assay for the qualitative detection of pesticide residues in agricultural samples. The assay is based on a reagent-mediated color change that occurs in the presence of commonly used organophosphate pesticides. Agricultural samples were prepared using standard extraction methods and subjected to the colorimetric reaction under controlled conditions. Visual color change was recorded and compared across treated and untreated samples to assess detection capability. The developed method demonstrated clear and reproducible color variation in pesticide-positive samples, while control samples showed no significant change. The assay requires minimal equipment, low reagent consumption, and can be performed within a short time frame, making it suitable for on-site screening applications. Although the method currently provides qualitative results, it shows strong potential as a preliminary screening tool for pesticide detection in field conditions. Future work will focus on quantitative validation using spectrophotometric or image-based analysis to enhance sensitivity and reproducibility. This study highlights the feasibility of developing accessible biosensing approaches for environmental monitoring and food safety applications in resource-limited settings.