The Use of a Solid Bismuth Microelectrode for Vanadium Quantification by Adsorptive Stripping Voltammetry in Environmental Water Samples

This paper presents for the first time the use of an environmentally friendly solid bismuth microelectrode for the voltammetric quantification of V(V) in natural water samples. These studies were designed to replace the film bismuth electrode that had been introduced to eliminate the conventional sensors based on highly toxic mercury. In the proposed procedure, V(V) is preconcentrated at the solid bismuth microelectrode surface via the formation of electroactive complexes with cupferron from a solution of 0.1-mol L⁻¹ acetate buffer, pH = 4.6 at a potential of −0.4 V. The linearity of the calibration graph is in the V(V) concentration range from 8 × 10⁻¹⁰ to 1 × 10⁻⁷ mol L⁻¹ with a preconcentration time of 1 min. The limit of detection (calculated as 3 σ) is 2.5 × 10⁻¹⁰ mol L⁻¹ for a preconcentration time of 1 min. It was also demonstrated that significant improvement in analytical parameters was achieved as a result of the activation of the solid electrode surface at a potential of −2.5 V for 2 s. The developed procedure is highly selective for the presence of foreign ions and organic compounds in tested samples. The accuracy of the recommended procedure was checked using SPS-WW1 waste water-certified reference materials of a complex composition, in which the concentration of V(V) determined by the proposed method was 95.1 ± 1.6 ng mL⁻¹. Moreover, in keeping with the outlined procedure, river, tap and rain water samples were analyzed without any pretreatment, and recovery values from 96% to 106% were obtained.