Glyphosate detection by voltammetric techniques. A comparison between statistical methods and an artificial neural network

Abstract

Glyphosate quantification methods are complex and expensive, and its control in natural water bodies is getting more important year after year. In order to find a new system that facilitates the detection of glyphosate, we present a comparison between two models to predict Glyphosate concentration in aqueous dissolutions. One of them is done by an Artificial Neural Network (ANN) embedded in a Microcontroller and the other one is done by statistic methods (Partial Least Squares) in a computer. From an analytical point of view, Voltammetric techniques have been selected to obtain electrochemical responses to different Glyphosate concentrations. In order to get them, a Voltammetry/Amperometry device designed by our research group and called FraPlus has been used. In this work we have selected two sensitive electrodes (Cobalt and Copper), ten different glyphosate concentrations and a train pulse made by nine different voltammetric pulses to build the models. The ANN developed model is able to properly relate data obtained by FraPlus and Glyphosate concentrations and the obtained value for regression coefficient (R) is 0.9998 and the PValue is 0.0. Taking into account these results, we propose this ANN model based in Voltammetric techniques working with Glyphosate concentrations in a buffer as an approach to Glyphosate detection in natural water bodies.

Glyphosate detection with ammonium nitrate and humic acids as potential interfering substances by pulsed voltammetry technique

“…This electronic device and measurement system has been described in detail in previous papers working with glyphosate [18] [29] and has been successfully used in food [38][39] [40], water analyses [41] and the determination of environmental parameters [42].…”

“…As in the previous works with glyphosate [18][29], pulsed voltammetry technique was used to apply an electric voltage to the utilized electrodes (working electrodes) when submerged in glyphosate dissolutions. Then the electric current that circulates through each electrode could be measured.…”

“…In the end, in order to guarantee a full contact of all the sensors, the overflowing resin of the metal sensor was sanded (Figure 1). The selection of the metal sensors used to develop the arrays has been made according to our previous experience [18][42] and papers published before [43] [44]. In addition, a calomel electrode has been used (Radiometer Analytical, XR 100) as reference electrode.…”

“…Attending to the experience acquired in previous works [18][42] [43] and the preliminary tests with glyphosate in buffer dissolution, a pulse train (figure 2) has been designed and used in order to carry out the voltammetric measurements. Electrochemical analyses have been done by using the FraPlusMini device to samples with five different concentrations of glyphosate, three different ones of ammonium nitrate, and three different ones of liquid humus dissolved on a buffer solution of 0.1M sodium dihydrogen phosphate adjusted to a pH of 6.7 with a few drops of NaOH.…”

“…Despite the lack of control and legislation of this herbicide in many countries [18], the USEPA is the worldwide legal reference in terms of limit concentrations for glyphosate in water bodies [19][20] [21], setting a maximum concentration of 0.7mg/l. In addition, the Health Canada Drinking Water Guidelines set 0.28mg/l as its Maximum Acceptable Concentration in drinking waters [22] [23].…”