Krystian Węgiel

The renewable bismuth bulk annular band working electrode: Fabrication and application in the adsorptive stripping voltammetric determination of nickel(II) and cobalt(II)

The paper presents the first report on fabrication and application of a user friendly and mercury free electrochemical sensor, with the renewable bismuth bulk annular band working electrode (RBiABE), in stripping voltammetry (SV). The sensor body is partly filled with the internal electrolyte solution, in which the RBiABE is cleaned and activated before each measurement. Time of the RBiABE contact with the sample solution is precisely controlled. The usefulness of this sensor was tested by Ni(II) and Co(II) traces determination by means of differential pulse adsorptive stripping voltammetry (DP AdSV), after complexation with dimethylglyoxime (DMG) in ammonia buffer (pH 8.2). The experimental variables (composition of the supporting electrolyte, pre-concentration potential and time, potential of the RBiABE activation, and DP parameters), as well as possible interferences, were investigated. The linear calibration graphs for Ni(II) and Co(II), determined individually and together, in the range from 1×10(-8) to 70×10(-8)molL(-1) and from 1×10(-9) to 70×10(-9)molL(-1) respectively, were obtained. The calculated limit of detection (LOD), for 30s of the accumulation time, was 3×10(-9)molL(-1) for Ni(II) in case of a single elements analysis, whereas the LOD was 5×10(-9)molL(-1) for Ni(II) and 3×10(-10)molL(-1) for Co(II), when both metal ions were measured together. The repeatability of the Ni(II) and Co(II) adsorptive stripping voltammetric signals obtained at the RBiABE were equal to 5.4% and 2.5%, respectively (n=5). Finally, the proposed method was validated by determining Ni(II) and Co(II) in the certified reference waters (SPS-SW1 and SPS-SW2) with satisfactory results.

Application of bismuth bulk annular band electrode for determination of ultratrace concentrations of thallium(I) using stripping voltammetry.

A study of a new type of mercury-free working electrode - the bismuth bulk annular band working electrode (BiABE) - applied for thallium(I) detection via differential pulse anodic stripping voltammetry (DP ASV), preceded by the complexation of interfering ions (Cd(2+), Pb(2+)) with EDTA in an acetate buffer (pH 4.5), is reported. The optimisation of experimental conditions included selection of the appropriate supporting electrolyte solution, potential and time of preconcentration, and DP mode parameters. The peak current was proportional to the concentration of Tl(I) in the range from 0.5 to 49nmolL(-1) (R=0.9992) and from 0.05 to 1.4nmolL(-1) (R=0.9987) for accumulation times of 60s and 300s, respectively. For 60s of accumulation time, the LOD was 0.005nmolL(-1) (1ngL(-1)) (at S/N=3), and the sensitivity of 18.5nA/nM was achieved. The relative standard deviation for 4.9nmolL(-1) of Tl(I) was 4.3% (n=5). Finally, the proposed method was successfully applied to determine Tl(I) in the certified reference materials-waters (SPS-SW1 and SPS-SW2) as well as the spiked tap and river water samples.

Voltammetric determination of iron with catalytic system at a bismuth bulk annular band electrode electrochemically activated

The short-time activated bismuth bulk annular band working electrode (BiABE) has been applied for catalytic differential pulse voltammetric (DPV) determination of trace concentrations of iron in an alkaline solution, preceded by complexation of triethanolamine. The reduction current of Fe(III) was catalytically enhanced in the presence of bromate. The experimental variables such as potential and time of activation, composition of the supporting electrolyte, differential pulse (DP) mode parameters, and influence of possible interferences on the Fe(III) signal response were tested. In the optimized conditions, the peak current was found to be proportional to the concentration of Fe(III) over the range from 1 to 476 μg L−1 (1.8 × 10−8 to 8.5 × 10−6 mol L−1) with R = 0.9993. The limit of detection (LOD) was 0.28 μg L−1 (5.0 × 10−9 mol L−1) (at S/N = 3), and sensitivity was 0.011 μA μg−1 L−1. The relative standard deviation (RSD) for 40 μg L−1 of Fe(III) was 3.3% (n = 5). The presented results were obtained without any preconcentration time. Finally, the proposed method was successfully applied for the determination of the total amount of Fe in the certified reference surface water, as well as tap and river water samples.