3 research outputs found
Direct Voltammetric Determination of Total Iron with a Gold Microelectrode Ensemble
The behavior of the Fe(II)/(III) redox system at a Au microelectrode ensemble (Au-MEE) based on a solid composite by means of direct and cyclic voltammetric analysis (VA) is reported. With a simple electrode activation and sample preparation, the influence of dissolved organic substances was eliminated, providing highly sensitive results. The analytical signal was based on the maximum cathodic current (I) of the first derivative (dI/dE), and iron determination within the 0.002-0.04mgL -1 range was studied. A sensitive LOD (3σ) value of 0.7μgL -1 for total iron concentration was calculated; total iron determination in different waters was shown. © 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim
Gold microelectrode ensembles: cheap, reusable and stable electrodes for the determination of arsenic (V) under aerobic conditions
The determination of total arsenic through As(V) anodic stripping voltammetry (ASV) is, in some cases, preferable over As(III) ASV. The As(V) ASV procedure has no chemical reduction step from As(V) into As(III), which results in decreased analysis time and no contamination from reducting reagents. A simple and reliable procedure of As(V) determination is proposed. Anodic stripping determination of trace As(V) at gold microelectrode ensembles in diluted HCl solution in the presence of dissolved oxygen is shown. The electrode is based on a carbon black (30%)-polyethylene composite. The sensor was prepared by gold electrodeposition on the surface of the composite electrode. The given sensor is cheap, reliable and stable, especially when electrochemical activation is employed. The experimental parameters for the electrochemical determination were optimized, namely 0.005M HCl as the background electrolyte, the deposition potential -2.2V (versus Ag/AgCl in 1M KCl) and 180mVs-1 linear scan rate. Calibration curves were obtained and were linear in [As(V)] over the 1.5-45 μgL-1 range, with a LOD of 0.5 μgL-1. The effect of common interfering species is studied. The electrochemical behaviour of As(III) form is studied in the same experimental conditions. It was found that As(III) is deposited at lower potentials (starting at -0.6 V) and the sensitivity of As(III) detection is higher, but dependant on the presence of dissolved oxygen. The speciation of inorganic forms of arsenic is discussed. © 2013 Taylor and Francis