Determination of lead and cadmium by anodic stripping voltammetry at bismuth film electrodes following double deposition and stripping steps

• Two working electrodes were applied in stripping analysis.
• Working electrodes have very different surface areas.
• Double deposition and stripping steps were used for cadmium and lead determination.
• The detection limits were lowered significantly.

The double deposition and stripping steps were proposed to increase the sensitivity in anodic stripping voltammetry of lead and cadmium. Two in situ plated bismuth film electrodes at drastically different surface areas were used for the measurements. Cadmium and lead were at first deposited at the electrode with a large surface area. When the deposition step at the electrode was finished, the electrode was placed at a short distance opposite the small one. Then Cd(II) and Pb(II) stripped from the first electrode were deposited at the second electrode. Taking into account the small volume of space between the electrodes, the concentration of Pb(II) and Cd(II) between the electrodes was drastically higher than that in the bulk solution. The deposition step at the second electrode was performed from the solution with a higher concentration of the determined ions, and so the detection limit was lowered. Calibration was performed following deposition times of 300 and 120 s at the first and the second electrode, respectively. Under such conditions the detection limits of 1.8 × 10−10 and 4.5 × 10−11 mol L−1 for Pb(II) and Cd(II) were obtained, respectively.