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.
Highlights
Glyphosate is a non-selective broad-spectrum systemic herbicide of widespread use in agriculture [1]
Following our interest in the development of new electrodes and electronic tongue devices [33,34,35,36,37,38,39,40] for their application in a wide range of problems, we report the design of a voltammetric electronic tongue which consists in three metallic electrodes (i.e., Co, Cu and Pt) and their use in detecting glyphosate in aqueous samples
The electronic tongue was able to discriminate the presence of glyphosate and those samples containing this herbicide appeared well separated in both assays using either the rotating
Summary
Glyphosate (see Figure 1) is a non-selective broad-spectrum systemic herbicide of widespread use in agriculture [1]. In the case of the studies using HPLC chromatography, the reached limits of detection were in the range of g/mL when the sample was conditioned by pre- or post-column derivatization protocols and coupled to mass analysis (HPLC/MS/MS) Another reported approach found in the literature to detect glyphosate was its derivatization with a chromophore or fluorophore and the use of techniques such as. Multivariate analyses, including principal component analysis (PCA) and partial least square (PLS) techniques have been applied to build suitable management and prediction models for the determination of glyphosate concentrations It has been studied the effect of calcium and humic acids in glyphosate detection
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