Direct electrochemical detection of glyphosate at carbon paste electrode and its determination in samples of milk, orange juice, and agricultural formulation

Abstract

This paper describes a simple, inexpensive, highly sensitive, selective, and efficient electrochemical method to determine glyphosate (GLY) in samples of milk, orange juice, and agricultural formulation. The oxidation reaction on the electrode surface was electrochemically characterised by cyclic voltammetry (CV) and square wave voltammetry (SWV). The investigation of GLY at carbon paste electrode revealed a non-reversible oxidation peak at +0.95 V versus Ag/AgCl, which was used for electrochemical detection of GLY. The operating parameters (pH, frequency, step potential, and amplitude) were optimised in relation to the peak current intensity, and a calibration curve was set up in a concentration range of 4.40 × 10⁻⁸–2.80 × 10⁻⁶ mol L⁻¹, with a detection limit of 2 × 10⁻⁹ mol L⁻¹. After calibration curve was plotted, the developed procedure was applied to determine GLY in previously contaminated samples: milk and orange juice, and in a commercial formulation, obtaining recovery values between 98.31% and 103.75%. These results show that the proposed method can be used for GLY quantification in different samples with high sensitivity, specificity, stability, and reproducibility.

Keywords:

• Glyphosate
• carbon paste electrode
• milk
• orange juice
• agricultural formulation

Acknowledgments

The authors wish to thank FUNDECT-MS, FINEP, CAPES, and CNPq for the grants awarded.