A procedure for the determination of In(III) by anodic stripping voltammetry following double deposition and stripping steps was described. Two environmentally friendly electrodes with different surface areas – glassy carbon macroelectrode and an ensemble of carbon composite microelectrodes – modified with bismuth films were used for the measurements. Parameters affected In(III) determination were optimized. Under optimized conditions the calibration graph was linear from 5 × 10⁻¹⁰ to 2 × 10⁻⁸ mol L⁻¹ following deposition time of 300 s at both working electrodes. The application of double deposition and stripping steps led to a very low detection limit of indium determination of 1.5 × 10⁻¹⁰ mol L⁻¹. Possible interferences from contaminant metal ions were studied and the procedure of elimination of Cd(II) effect on In(III) signal was proposed. The analysis of natural water sample was successfully performed with the use of the presented methodology.

For the first time a solid bismuth microelectrode was utilized for anodic stripping voltammetry in the course of Tl(I) ions determination. The proposed solid bismuth microelectrode ( ϕ 25 μ m) is more environmentally friendly sensor in comparison to bismuth film electrodes as bismuth ions are not added to the supporting electrolyte for bismuth film formation. Furthermore, an amount of metallic bismuth needed for fabrication of proposed sensor is significantly minimized as compared to solid bismuth electrode with a large surface area. Furthermore, the measurements may be carried out from unstirred solutions that gives possibility of performing fields analysis. The optimization of the analytical parameters of Tl(I) determination procedure was presented. A calibration graph for Tl(I) determination was linear in the range from 2 × 10 ⁻⁹ to 2 × 10 ⁻⁷ mol l ⁻¹ (deposition time of 120 s). The detection limit for thallium ions determination was 8.3 × 10 ⁻¹⁰ mol l ⁻¹ for deposition time of 120 s. Repeatability of the proposed procedure calculated as RSD% for Tl(I) at concentration of 2 × 10 ⁻⁸ mol l ⁻¹ was 5.2% (n = 5). The accuracy of the proposed procedure was successfully checked by analysis of a lake water certified reference material TM 25.5.