Colorimetric Sensing of Glyphosate in Environmental Water Based on Peroxidase Mimetic Activity of MoS₂ Nanosheets

Glyphosate was found for the first time to inhibit the catalytic activity of MoS₂ nanosheets, which could catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine by H₂O₂ to produce a colorimetric reaction. In the presence of glyphosate, the absorbance and blue color of the system was decreased. Therefore, a simple and sensitive colorimetric sensing method for glyphosate based on the peroxidase mimetic activity of MoS₂ nanosheets was developed. A linear relationship between the absorbance change and concentration of glyphosate was observed over the range of 0.4—2.0 μg/mL (R ² = 0.993) with a detection limit (3Ω/S) of 0.087 μg/mL. The colorimetric sensing method was simple, rapid, specific and sensitive, and the detection limit of 0.087 μg/mL is lower than the maximum contaminant level of glyphosate in drinking water set by the Environment Protection Agency of USA and World Health Organization. This method was applied to detect glyphosate in environmental water samples with satisfactory results.