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We examined the use of a bismuth-glassy carbon (Bi/C) composite electrode for the determination of trace amounts of lead and cadmium. Incorporated bismuth powder in the composite electrode was electrochemically dissolved in 0.1M acetate buffer (pH 4.5) where nanosized bismuth particles were deposited on the glassy carbon at the reduction potential. The anodic stripping voltammetry on the Bi/C composite electrode exhibited well-defined, sharp and undistorted peaks with a favorable resolution for lead and cadmium. Comparing a non-oxidized Bi/C composite electrode with an in-situ plated bismuth film electrode, the Bi/C composite electrode exhibited superior performance due to its much larger surface area. The limit of detection was 0.41 microg/L for lead and 0.49 microg/L for cadmium. Based on this study, we are able to conclude that various types of composite electrodes for electroanalytical applications can be developed with a prudent combination of electrode materials.

Abstract: By combining a screen-printing method with an electrochemical reduction process, an electrochemical sensor to measure trace amounts of lead and cadmium was newly designed, fabricated and characterized. Bismuth oxide was printed on the electrode surface, and it was then electrochemically reduced to bismuth at a potential of −1.2V in 0.1M KOH. The stability of the fabricated Bi electrode was evaluated by repetitive measurements, and the interference of copper ions was investigated. The concentrations of lead and cadmium were also measured by square wave anodic stripping voltammetry. Bismuth film, reduced from screen-printed bismuth oxide, showed a well-defined and reproducible stripping response. The electrode exhibited linear behavior in the range of 20–100μg/L of lead and cadmium (correlation coefficients: 0.999 and 0.998, respectively) with detection limits of 2.3μg/L for lead and 1.5μg/L for cadmium. The applicability of the electrode to real samples was evaluated and the results were in good agreement with ICP-MS analysis. These results facilitate the widespread use of screen-printing techniques for the preparation of electrochemical sensors. [Copyright &y& Elsevier]

Abstract: A bismuth-modified carbon nanotube electrode (Bi-CNT electrode) was employed for the determination of trace lead, cadmium and zinc. Bismuth film was prepared by in situ plating of bismuth onto the screen-printed CNT electrode. Operational parameters such as preconcentration potential, bismuth concentration, preconcetraion time and rotation speed during preconcentration were optimized for the purpose of determining trace metals in 0.1M acetate buffer solution (pH 4.5). The simultaneous determination of lead, cadmium and zinc was performed by square wave anodic stripping voltammetry. The Bi-CNT electrode presented well-defined, reproducible and sharp stripping signals. The peak current response increased linearly with the metal concentration in a range of 2–100μg/L. The limit of detection was 1.3μg/L for lead, 0.7μg/L for cadmium and 12μg/L for zinc (S/N=3). The Bi-CNT electrode was successfully applicable to analysis of trace metals in real environments. [Copyright &y& Elsevier]