Simultaneous Anodic Stripping Voltammetric Determination of Pb and Cd, Using a Vibrating Gold Microwire Electrode, Assisted by Chemometric Techniques

Simultaneous anodic stripping voltammetric determination of Pb and Cd is restricted on gold electrodes as a result of the overlapping of these two peaks. This work describes the quantitative determination of a binary mixture system of Pb and Cd, at low concentration levels (up to 15.0 and 10.0 mu gL(-1) for Pb and Cd, respectively) by differential pulse anodic stripping voltammetry (DPASV; deposition time of 30s), using a green electrode (vibrating gold microwire electrode) without purging in a chloride medium (0.5M NaCl) under moderate acidic conditions (HCl 1.0mM), assisted by chemometric tools. The application of multivariate curve resolution alternating least squares (MCR-ALS) for the resolution and quantification of both metals is shown. The optimized MCR-ALS models showed good prediction ability with concentration prediction errors of 12.4 and 11.4% for Pb and Cd, respectively. The quantitative results obtained by MCR-ALS were compared to those obtained with partial least squares (PLS) and classical least squares (CLS) regression methods. For both metals, PLS and MCR-ALS results are comparable and superior to CLS. For Cd, as a result of the peak shift problem, the application of CLS was unsuitable. MCR-ALS provides additional advantage compared to PLS since it estimates the pure response of the analytes signal. Finally, the built up multivariate calibration models, based either in MCR-ALS or PLS regression, allowed to quantify concentrations of Pb and Cd in surface river water samples, with satisfactory results.