Detection of herbicide glyphosates based on an anti-aggregation mechanism by using unmodified gold nanoparticles in the presence of Pb2+

In this study, a new detection method for glyphosate (GPS) based on an anti-aggregation mechanism by using gold nanoparticles (AuNPs) is proposed. A certain amount of Pb2+ can cause the aggregation of AuNPs because of electrostatic interactions and the color of the solution changed from red to gray. However, in the presence of GPS, the above-mentioned process can be strongly hindered due to the chelation between GPS and Pb2+. Based on this anti-aggregation mechanism, the colorimetric detection method exhibits excellent sensitivity for GPS. The limit of detection (LOD) is 0.5 μM by the naked eye and 2.38 nM by UV-vis spectroscopy. The selectivity of the AuNP detection system for GPS is excellent compared with other pesticides. A good linear relationship (R2 = 0.99695) between the absorption intensity ratio and GPS concentrations indicates that our probe can be used for the quantitative assay of GPS. The detection method has been successfully used for detecting GPS in real environmental samples.