Development and Comparison of New Voltammetric Procedures for the Determination of In(III) Using ASV and AdSV Techniques with SBiµE as an Green Working Electrode

The article describes innovative procedures for determining In(III) using anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) with cupferron as a chelating agent. In both procedures, an environmentally friendly solid bismuth microelectrode (SBiµE) with a diameter of 25 µm was used as the working electrode. In both procedures, 0.1 mol L^-1 acetate buffer with a pH of 3.0 ± 0.05 was used as the supporting electrolyte. The electrochemical measurement conditions were as follows: -2.4 V for a 20 s activation step and -1.2 V for a 20 s accumulation step for ASV, and -2.5 V for a 45 s activation step and -0.65 V for a 10 s accumulation step for AdSV. The signal was recorded as a result of a positive potential change from -1.0 to -0.3 V in the case of the ASV procedure and as a result of a negative potential change from -0.4 to -1.0 V in the case of the AdSV procedure. The calibration graph was linear from 5 × 10^-9 mol L^-1 to 5 × 10^-7 mol L^-1 with a detection limit of 1.4 × 10^-9 mol L^-1 for ASV and from 1 × 10^-9 mol L^-1 to 1 × 10^-7 mol L^-1 with a detection limit of 3.9 × 10^-10 mol L^-1 for AdSV. The effect of interferents such as surfactants, humic substances and EDTA on the analytical signal was compared in the case of signal recording using the ASV technique with the signal recorded using the AdSV technique. Based on the results obtained, it was determined how the charge of interferents affects the signal depending on the technique used. To validate the practical application of the developed procedures, an analysis of In(III) recovery from samples of the Baltic Sea and Synthetic Sea Water was performed.