Free Zn2+ determination in natural freshwater of the Pyrenees: towards on-site measurements with AGNES
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An on-site methodology has been developed for the direct determination of free Zn2+ with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) in freshwaters. This implementation includes: i) the use of screen printed electrodes, which provide good limits of detection and easy transportation and deployment; ii) no need for sample purging; iii) a calibration in a synthetic river solution that reproduces well the speciation changes of the natural samples and allows the oxygen interferences to be minimised; iv) the addition of a background electrolyte up to 0.01 mol L-1 in both the calibration and freshwater samples; v) chemical stripping chronopotentiometry as the quantification stage of AGNES. This procedure minimizes the effects of working at low ionic strength and in the presence of dissolved oxygen. In the laboratory, the methodology was checked with different natural samples taken from rivers Garonne, Gave de Cauterets and Gave de Pau in the Pyrenees. Results appeared in good agreement with theoretical estimations computed from Visual Minteq. On-site measurements were performed for the first time with AGNES in the Gave de Cauterets in Soulom (France) and the results were corroborated with purged measurements performed in the laboratory.
Is part ofEnvironmental Chemistry, 2015, vol. 12, núm. 3, p. 329-337
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Determination of free metal ion concentrations using screen-printed electrodes and AGNES with the charge as response function Parat, C.; Aguilar Camaño, David; Authier, L.; Potin-Gautier, M.; Companys Ferran, Encarnació; Puy Llorens, Jaume; Galceran i Nogués, Josep (Wiley, 2011)AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) has been implemented with screen-printed electrodes (SPE) for the determination of the free concentration of Zn2+, Cd2+ and Pb2+. For SPE, the stripped charge ...
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Aguilar Camaño, David; Galceran i Nogués, Josep; Companys Ferran, Encarnació; Puy Llorens, Jaume; Parat, C.; Authier, L.; Potin-Gautier, M. (Royal Society of Chemistry, 2013)The reduction of oxygen increases pH in the surroundings of an electrode. A theoretical model estimates the steady-state pH profile from the surface of the electrode up to the bulk solution. A very simple formula predicts ...