Voltammetric determination of Cu(II), Pb(II), Cd(II) and Zn(II) in certified environmental sample and multivariate evaluation mixture of Pb(II), Tl(I) and Cd(II) with overlapping waves

Abstract

Using the differential pulse anodic stripping voltammetry technique, the metallic ions Cd(II), Pb(II), Zn(II) and Cu(II) were determined, in a first step, in a sediment sample certified by the “National Institute of Standards & Technology”, to certify this methodology as a standard routine laboratory technique. In the second stage, the multivariate calibration was used for the individual quantitative determination of the electroactive chemical species Pb(II), Cd(II) and Tl(I) that present partially superimposed voltammetric waves. In the determination of Cd(II), Pb(II), Zn(II) and Cu(II) ions, the voltammetric waves were very distinct within the worked potential range and the standard additions showed linearity in view of the increase in ion concentration . On the other hand, for the individual determination of Pb(II), Cd(II) and Tl(I) ions, considering the overlapping of voltammetric waves, it was necessary to use multivariate calibration methods that extend the basic idea of modeling and forecasting that are used in univariate calibration for multiple dependent and independent variables. In this work, the Partial Least Squares Method – PLS was used, which is a linear regression technique of multivariate statistics that relates output variables and input variables, in which there is a high degree of correlation between them.