Redox magnetohydrodynamics enhancement of stripping voltammetry of lead(ii), cadmium(ii) and zinc(ii) ions using 1,4-benzoquinone as an alternative pumping species

Abstract

Differential pulse anodic stripping voltammetry (DPASV) coupled with redox-magnetohydrodynamics (MHD) is used to enhance the anodic stripping voltammetry (ASV) response using a mercury thin film–glassy carbon electrode. The sensitivity increased to at least a factor of two (at 1.2 T) and is facilitated by using 20.0 mmol L⁻¹1,4-benzoquinone as an alternative pumping species to enhance ASV by redox-MHD. The MHD force formed by the cross-product of ion flux with magnetic field induces solution convection during the deposition step, enhancing mass transport of the analytes to the electrode surface and increasing their preconcentrated quantity in the mercury thin film. Therefore, larger ASV peaks and improved sensitivities are obtained, compared with analyses performed without a magnet. The influence of pH, 1,4-benzoquinone concentration, accumulation potential, and time are also investigated. Detection limits of 0.05, 0.09 and 2.2 ng mL⁻¹Cd(II), Pb(II) and Zn(II) were established with an accumulation time of 65 s. The method is used for the analysis of Cd(II), Pb(II) and Zn(II) in different water samples, certified reference materials, and saliva samples with satisfactory results.