Oxidized Glyphosate Detection by Polypyrrole Imprinted on Copper: A Step Towards Impedimetric Affinity Sensors

Abstract

Glyphosate is an aminophosphonate chemical compound part of most commercial herbicides. Due to its wide use in agriculture, it is found in water bodies as an emerging contaminant. This work uses a polypyrrole-based molecularly imprinted polymer as a recognition layer to detect glyphosate. A glyphosate oxidation study was carried out with a non-imprinted polymer (NIP) and a molecularly imprinted polymer (MIP) deposited on a planar Cu electrode using the cyclic voltammetry (CV) technique. Parameters such as scan rate and glyphosate concentration were varied. Glyphosate oxidation tests were performed using the linear voltammetry technique on NIP/Cu and MIP/Cu electrodes and at the highest glyphosate concentration used in the experiments. In conjunction, Raman spectroscopy measurements were performed before and after glyphosate oxidation. Then, impedance spectroscopy  measurements were carried out before and after of the linear scan in the presence of glyphosate. Percentage changes were obtained from the impedance measurements. The maximum change in impedance for each glyphosate concentration was achieved around 1 Hz. According to these results, the printed MIP/Cu electrode sites reduce glyphosate oxidation potential due to their higher affinity for glyphosate. Furthermore, low detection limits (LODs) are obtained.