Glyphosate Detection by Means of a Voltammetric Electronic Tongue and Discrimination of Potential Interferents

Abstract

A new electronic tongue to monitor the presence of glyphosate (a non-selective systemic herbicide) has been developed. It is based on pulse voltammetry and consists in an array of three working electrodes (Pt, Co and Cu) encapsulated on a methacrylate cylinder. The electrochemical response of the sensing array was characteristic of the presence of glyphosate in buffered water (phosphate buffer 0.1 mol·dm−3, pH 6.7). Rotating disc electrode (RDE) studies were carried out with Pt, Co and Cu electrodes in water at room temperature and at pH 6.7 using 0.1 mol·dm−3 of phosphate as a buffer. In the presence of glyphosate, the corrosion current of the Cu and Co electrodes increased significantly, probably due to the formation of Cu2+ or Co2+ complexes. The pulse array waveform for the voltammetric tongue was designed by taking into account some of the redox processes observed in the electrochemical studies. The PCA statistical analysis required four dimensions to explain 95% of variance. Moreover, a two-dimensional representation of the two principal components differentiated the water mixtures containing glyphosate. Furthermore, the PLS statistical analyses allowed the creation of a model to correlate the electrochemical response of the electrodes with glyphosate concentrations, even in the presence of potential interferents such as humic acids and Ca2+. The system offers a PLS prediction model for glyphosate detection with values of 098, −2.3 × 10−5 and 0.94 for the slope, the intercept and the regression coefficient, respectively, which is in agreement with the good fit between the predicted and measured concentrations. The results suggest the feasibility of this system to help develop electronic tongues for glyphosate detection.

Using an automatic pulse voltammetric electronic tongue to verify the origin of honey from Spain, Honduras, and Mozambique

“…The PLS model was calibrated with 66% of the data set and validated with the remaining 33% and the assessment was carried out by comparing real versus predicted physicochemical analysis. The parameters considered in the model were: correlation coefficient (r 2 ), a, b (from the simplest linear model: y = ax + b ) and the root mean square error of prediction (RMSEP) as the most common metric to measure the accuracy of this methodology …”

An Electrochemically Synthesized Nanoporous Copper Microsensor for Highly Sensitive and Selective Determination of Glyphosate

“…However, as Glyp is not an electrochemically active compound within the accessible potential range, approaches based on indirect electrochemical sensing have been developed using different electrodes such as gold, platinum, nickel, copper, and cobalt. [20][21][22][23] In these previous studies, non-noble metal electrodes, especially copper, were a preferred choice because noble metals electrodes suffer from surface fouling from strong irreversible adsorption of Glyp amino and carboxylic moieties. Copper-based organometallic compounds like copper phthalocyanine composited with carbon nanotubes were also used for direct voltammetric determination of Glyp, [24] and the developed sensor showed very high sensitivity and detection limit in the nmol L À 1 range, which is below the mandated guidelines.…”

“…Then, a relationship between the reduction in the cathodic current and the concentration of Glyp in the solution can be established. [20][21][22] Taking into account the complexation tendency of copper cations with Glyp, the use of nanoporous copper (NPC) with very high surface area can be an ideal sensing material for the development of an ultra-high sensitivity method for this pesticide detection.…”

Glyphosate Detection: An Innovative Approach by Using Chemoresistive Gas Sensors

“…In particular, the most used techniques are gas and liquid chromatography (GC and LC), especially based on derivatising agents [3,4]. Immunosensors, optical and colorimetric sensors represent an effective alternative together with more innovative methods, such as electronic tongue in water [5,6]. The occurrence and behavior of atmospheric transport of glyphosate are still largely unknown even though glyphosate is the most widely used herbicide in the world.…”