In the first part of this project, differential pulse anodic stripping voltammetry (DPASV) coupled with redox magnetohydrodynamics (MHD) to enhance the anodic stripping voltammetry (ASV) response has been shown to yield a quantitative simultaneous determination of lead, cadmium and zinc ions determination in water samples using mercury thin film glassy carbon electrode. The sensitivity was facilitated by using 20.0 mmol L^-1 quinone as a new reagent to enhance ASV by redox MHD in the presence of a magnet. This Lorentz force induces solution convection during the deposition step, enhancing the mass transport of analytes to the electrode and increasing their preconcentrated quantity in the mercury thin film. Therefore, larger ASV peaks and improved sensitivities are obtained, compared to analyses performed without a magnetic field to produce a high cathodic current which generates a significant Lorentz force. Using 1 min as an accumulation time and accumulation potential -1.10 V, detection limits of 0.05, 0.09 and 2.3 ng mL^-1 Cd(II), Pb(II) and Zn(II) has been established. The calibration curves were constructed for 0.07 – 70.0 ng mL^-1 Cd(II), 3.5 – 220.0 ng mL^-1 Zn(II) and 0. 1 – 60.0 ng mL^-1 Pb(II) under the optimized conditions, respectively.

In the second of this project, A new carbon-based mercury thin-film electrode (CBMFE) consisting of screen-printed carbon (SPC) on a low temperature co-fired ceramic (LTCC) substrate was used for simultaneous determination of ultra trace amounts of cadmium(II), Zinc(II), and lead(II) using differential pulse anodic stripping voltammetry. Analysis with CBMFE has very good reproducibility (≤ 4%) and long-term stability (>500 measurement cycles). The electrode can be prepared easily using an acetate buffer solution (pH 4.0) containing 10 mmol L^-1 mercuric nitrate and 50 mmol L^-1 potassium thiocyanate with an applied potential of -0.90 V vs. Ag/AgCl (saturated KCl) for 60 s. The calibration plot was linear over the range 0.5 – 60.0 ng mL^-1 Cd(II) 8.0 – 200.0 ng mL^-1, Zn(II) and 0.6 – 70.0 ng mL^-1  Pb(II). Detection limits of 0.25 , 0.45 and 7.5 ng mL⁻¹ were obtained for Cd(II) , Pb(II) and Zn(II), respectively.

Keywords: Permanent magnets; Quinone; Lorantz force; Redox magnetohydrodynamic; Carbon mercury film electrode; Screen-printed gold on a ceramic (LTCC) substrate; Potassium thiocyanate.