Bismuth-Trifluoride Modified Carbon Paste Electrode for Electrochemical Stripping Analysis of Heavy Metals

In this article, a novel type metal-film based electrode, bismuth trifluoride-bulk-modified carbon paste electrode (BiF3-CPE), is for the first time reported and examined in electrochemical stripping analysis for determination of selected heavy metals at the ppb (mu g.L-1) concentration level. Optimal amount of bismuth trifluoride, as the source of in-nascenti generated bismuth film, was 10% (w/w). All important experimental and instrumental parameters have been optimized in the square-wave anodic stripping voltammetric mode when using Cd(II) and Pb(II) as the model ions. As found, BiF3-CPE has exhibited a linear response in several concentration ranges tested, starting from the low ppb level (2-12 mu g.L-1) via a mid level (10-150 mu g.L-1), up to rather high concentrations in the range of 200-120 mu g.L-1; the repeatability of (10%)BiF3-CPE, expressed by the RSD, being +/- 1.7 % (for n=10) for Cd(II) and +/- 1.4% for Pb(II). Interferences from selected heavy metals were also studied and no serious negative effects revealed. Finally, the (10%)BiF3-CPE has been examined in analysis of certified reference material (sewage sludge with extremely high content of Pb) with a satisfactory agreement with the declared value (2233.2 mu g.g(-1) versus 2290 +/- 110 mu g.g(-1) Pb in the CRM).