Visual detection of glyphosate in environmental water samples using cysteamine-stabilized gold nanoparticles as colorimetric probe

In this study, a novel colorimetric method for rapid, sensitive and low-cost detection of glyphosate was developed using cysteamine-stabilized gold nanoparticles (CS-AuNPs). The CS-AuNPs could be aggregated easily in the presence of glyphosate through electrostatic interaction in acidic medium, resulting in a shift in the surface plasmon band and a consequent color change from red to blue (or purple). Therefore, the content of glyphosate could be determined by monitoring with the naked eyes or a UV-Vis spectrophotometer. The detection limit of the present method for glyphosate was 5.88 × 10−8 M, with the linear range of 0.500–7.00 μM. The proposed method is a promising approach for on-site screening of glyphosate content in environmental water samples without using any costly instruments.