Simultaneous voltammetric determination of four carbamate pesticides with the use of chemometrics

Voltammetric behaviour of four carbamate pesticides, propoxur, isoprocarb, carbaryl and carbofuran, was investigated, and a method was developed for the simultaneous determination of these compounds. This was based on their anodic voltammetric behaviour observed following their alkaline hydrolysis, which produced electroactive phenol derivatives. It was found that by applying the differential pulse voltammertric (DPV) method in the presence of perchloric acid, the four compounds have well defined voltammetric oxidation waves with peak potentials at 712, 888, 664, and 688 mV, respectively. For each compound, a linear calibration was obtained in the concentration range of 1.0-30 mg l−1. Serious overlapping of individual voltammetric peaks was observed for the mixtures of these four compounds, and to facilitate the resolution of these complex voltammograms, different calibration models were investigated based on four different chemometrics methods, viz., classical least squares (CLS), principal component regression (PCR), partial least squares (PLS) and radial basis function-artificial neural networks (RBF-ANN). The prediction ability of these models were tested with the use of a data set constructed from synthetic solutions of the four pesticides. The analytical performance of the prediction models was characterized with the use of various figures of merit, and the best results were obtained with the PC-RBF-ANN method (%RPET = 5.6 and %Recovery (average) = 100). This method was then applied for the determination of the four pesticides in different water samples.