Glyphosate detection from commercial formulations: comparison of screening analytic methods based on enzymatic inhibition

Two simple and environmentally friendly methods based on enzymatic inhibition for the rapid determination of glyphosate in commercial formulations were compared. The principle of the methods is based on the response obtained by means of spectrophotometry (UV/Vis-SPD) and spectrofluorimetry (FLD), from the reaction of the peroxidase enzyme with its substrates, before and after incubation in glyphosate solutions. Glyphosate inhibits the activity of the enzyme, causing a decrease in its response. The UV/Vis-SPD was performed in Eppendorf tubes while the FLD was in microwell plates. The proposed methods were able to quantify glyphosate in the concentration ranges from 3.4 to 20 mg L⁻¹ with a limit of detection of 2 mg L⁻¹ and from 7 to 1000 μg L⁻¹ with a limit of detection of 4 μg L⁻¹ by UV/Vis-SPD and FLD, respectively. The FLD was more sensitive, simpler and faster than UV/Vis-SPD. The methods were applied to the detection of glyphosate in commercial formulations with percentage of declared dose from 82% to 108%. Therefore, these methods could be applied to glyphosate detection from commercial formulations in environmental samples.