Recent advances in anodic stripping voltammetry with bismuth-modified carbon paste electrodes

In this article, the results of some recent investigations on two types of bismuth-modified carbon paste electrodes are presented. In the first study, the bismuth-film carbon paste electrode (BiF-CPE) operated in situ and employed in anodic stripping voltammetry of Cd(II) and Pb(II) at the low μg L ^-1 level was of interest in view of choosing the proper Bi(III)-to-Me(II) concentration ratios (where Me: Pb or Cd). Such optimization has resulted in significant improvement of detection limits down to 1.0 μg L^-1 Cd and 0.8 μg L^-1 for Pb, which allowed us to apply the BiF-CPE for analysis of selected real samples of tap and sea water. The BiF-CPE was also further investigated for its application in highly alkaline media. In this case, attention was focused on the complex-forming capabilities of the OH ions and their effect on the anodic stripping characteristics of some heavy metals (i.e. Cd, Pb, Tl) as well as upon the formation of the bismuth film itself. The last example deals with the continuing characterization of the recently introduced carbon paste electrodes modified with bismuth powder (Bi-CPEs) which combine the advantageous properties of carbon paste material with the favorable electrochemical properties of bismuth. Three series of electrodes, differing either in the content of metallic bismuth (from 8 to 50% w/w) or in the type of the carbon powder used (two spectroscopic types of graphite and powdered glassy carbon), were compared and the respective relations to the optimal carbon paste composition evaluated. Attractive electroanalytical performance of the Bi-CPE in anodic stripping voltammetry is demonstrated for selected model mixtures of heavy metals (Mn, Zn, Cd, Pb, Tl, and In).