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A novel solid bismuth microelectrode in combination with adsorptive stripping voltammetry is demonstrated as a simple and fast method for determination of tin. The proposed method includes the formation of a tin complex with cupferron in the solution and deposition on the solid bismuth microelectrode. The selection of the most optimal parameters determining the sensitivity of the elaborated procedure was made. Under optimized parameters (pH = 4.6; acetate buffer concentration: 0.1 mol l−1; cupferron concentration: 2 × 10−4 mol l−1; activation potential/time: −2.5 V/5 s; deposition potential/time: −0.6 V/40 s), a linear response of Sn(II) in the concentration range of 8 × 10−9 do 8 × 10−7 mol l−1 (r = 0.9984) was obtained with a detection limit of 2.1 × 10−9 mol l−1. The interferences of foreign ions and organic matrix of environmental water samples were carefully studied. The accuracy of the method was studied by analyzing certified reference materials SPS-WW1 Waste Water and SPS-SW1 Surface Water as well as Bystrzyca river and rain water, and passable results were obtained.

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.

An analytical procedure regarding the voltammetric determination of germanium(IV) by adsorptive stripping voltammetry (AdSV) exploiting the in situ plated bismuth film electrode (BiFE) is described. The use of mercury free electrode as a working electrode is the first time proposed in AdSV germanium determination. The method is based on adsorptive accumulation of the Ge(IV)-chloranilic acid complex at a BiFE by a nonelectrochemical process followed by the cathodic stripping step. Experimental variables, including bismuth and chloranilic acid concentrations, deposition potential and time were carefully optimized. Under optimized conditions the cathodic stripping peak current was directly proportional to the concentration of Ge(IV) in the range from 3 Â 10 À9 to 1.5 Â 10 À7 mol L À1 with the correlation coefficient 0.997. Because the AdSV technique could be invalidated due to real samples matrix the influence of foreign ions, surface active substances, and humic substances on the Ge(IV) signal was precisely examined. The satisfying minimization of potential matrix interferences was also suggested.Analytical results of natural water samples analysis showed that the proposed procedure of trace germanium(IV) determination is suitable for direct environmental water analysis.

An analytical procedure regarding the determination of selenium(IV) by anodic stripping voltammetry exploiting the in situ plated bismuth film electrode is described. Since organics are commonly present in untreated natural water samples, the use of Amberlite XAD-7 resin turns out to be quite important to avoid problems such as the adsorption of these compounds on the working electrode. The optimum circumstances for the detection of selenium in water using differential pulse voltammetry techniques were found to be as follows: 0.1 mol L−1 acetic acid, 1.9 × 10−5 mol L−1 Bi(III), 0.1 g Amberlite XAD-7 resin, and successive potentials of −1.6 V for 5 s and −0.4 V for 60 s, during which the in situ formation of the bismuth film on glassy carbon and the accumulation of selenium took place. The current of the anodic peak varies linearly with the selenium concentration ranging from 3 × 10−9 mol L−1 to 3 × 10−6 mol L−1 (r = 0.9995), with a detection limit of 8 × 10−10 mol L−1. The proposed procedure was used for Se(IV) determination in certified reference materials and natural water samples, and acceptable results and recoveries were obtained.