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

Abstract

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.