Justyna Robak

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.

First electrochemical study of the fungicide oxycarboxin

ABSTRACT In this article, the utility of a boron-doped diamond electrode for the determination of the fungicide oxycarboxin is demonstrated. For the first time, the square-wave voltammetry was employed in a quantitative determination of oxycarboxin on the boron-doped diamond electrode. It was found that oxycarboxin displays a well-expressed oxidation peak at a potential of ca. +1.5 V vs. Ag/AgCl in Britton–Robinson buffer with the maximum response in pH 4.0. As observed in cyclic voltammetry, oxycarboxin undergoes diffusion-controlled irreversible electrochemical oxidation. At optimised square-wave voltammetry parameters, the current response of oxycarboxin was linearly proportional to its concentration in the wide linear dynamic range of 8.0–100.0 μmol L−1 (2.1–26.7 mg L−1). The developed electroanalytical method yielded a relatively low limit of detection of 1.6 μmol L−1 (0.4 mg L−1), associated with high repeatability of the peak current expressed as relative standard deviation in the range of 1.1–2.9% for each concentration of oxycarboxin solution. This simple and sensitive method was proved to be suitable for an analysis of spiked river water samples with satisfactory results (relative standard deviation of 1.4%, recovery of 100.2%). The impact of possible interferences was tested and evaluated, and obtained results proved good selectivity of the proposed method. In addition, the influence of oxycarboxin on the corrosion properties of AISI 316 L stainless steel used as a construction material in farming was tested using potentiodynamic method, and a corrosive damage was characterised by means of scanning electron microscopy.