Simultaneous analysis of nitro compounds by Voltammetric method combined with the partial least squares (PLS) and the principal component regression (PCR)

Abstract

Nitro aromatic compounds exhibit a strong electrochemical behavior on hanging mercury drop electrodes (HMDE). The ability to simultaneously determine 6 nitro compounds including nitrobenzene (NB), 2-nitrophenol (2-NP), 3-nitrophenol (3-NP), 4-nitrophenol (4-NP), 2,4- dinitrophenol (DNP) and trinitrophenol (TNT) in the same samples was investigated by differential pulse Voltammetry. The method is based on the electrochemical process at HMDE in acetate buffer of pH 4.6. It was found that peak potentials of voltammetric reduction waves of NB, 2-NP, 3-NP and 4-NP appeared at – 0.332, – 0.281, – 0.311 and – 0.387 V respectively. Under the same conditions there are three peak potentials at -0.131, – 0.227, – 0.332 V for TNT and two peaks at tại – 0.221, – 0.332V for DNT. The peaks of these compounds are very close together. Due to the serious overlapping of Voltammetric peaks of these compounds in the mixtures, so that by a conventional Voltammetry it not possible to individually determine each compound. In this study, linear multivariate regression methods such as partial least squares (PLS), principal component regression (PCR) was used to resolve the overlapped Voltammograms. The obtained relative standard errors of both methods are within ± 10%. The PLS (10.8% RSEt) results in data better than PCR (11.8% RSEt).