Colorimetric Detection of 1-Naphthol and Glyphosate Using Modified Gold Nanoparticles

Given the high toxicity and carcinogenic properties of pesticides, reducing pesticide residues is crucial for mitigating water pollution and promoting sustainable development. In the present study, a novel colorimetric method using gold nanoparticles (AuNPs) was designed for the detection of target analytes. The Turkevich-Frens method was used to synthesize AuNPs, which were then modified with sodium nitrite and L-cysteine for the detection of 1-naphthol and glyphosate, respectively. Different assay conditions strongly influenced the detection performance of the modified AuNPs, so the assay conditions were optimized for further investigation. In the presence of the target analytes (1-naphthol and glyphosate) under the optimum assay conditions, the absorption peak at 520 nm shifted and a corresponding color change was observed. The limits of detection of 1-naphthol and glyphosate were determined to be 0.15 and 0.27 ppm, respectively. In addition, the modified AuNPs had high selectivity for the target analytes and did not exhibit interference in the presence of other substances. This novel colorimetric method was then applied to detect the target analytes in mineral water and tap water with acceptable results.