ISIDORE, a Probe for In Situ Trace Metal Speciation Based on the Donnan Membrane Technique and Electrochemical Detection Part 2: Cd and Pb Measurements during the Accumulation Time of the Donnan Membrane Technique

Estelle Ricard (1) , Jose-Paulo Pinheiro (2) , Isabelle Le Hécho (1) , Corinne Parat (3, 1)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
2 LIEC - Laboratoire Interdisciplinaire des Environnements Continentaux
3 LCABIE - Laboratoire de Chimie Analytique Bio-Inorganique et Environnement

The Donnan membrane technique (DMT), in which a synthetic or natural solution (the "donor") is separated from a ligand-free solution (the "acceptor") by a cation-exchange membrane, is a recognized technique for measuring the concentration of a free metal ion in situ, with coupling to electrochemical detection allowing for the quantification of the free metal ion directly on site. However, the use of the DMT requires waiting for the free metal ion equilibrium between the donor and the acceptor solution. In this paper, we investigated the possibility of using the kinetic information and showed that non-equilibrium experimental calibrations of Cd and Pb with the ISIDORE probe could be used to measure free metal concentrations under conditions of membrane-controlled diffusion transport. The application of this dynamic approach made it possible to successfully determine the concentration of free Cd in synthetic and natural river samples. Furthermore, it was found that the determination of free Cd from the slope was not affected by the Ca concentration ratio between the acceptor and donor solution, as opposed to the traditional approach based on Donnan equilibrium. This ISIDORE probe appears to be a promising tool for determining free metal ions in natural samples.

Mots clés: Donnan membrane technique screen-printed electrode free ion concentrations dynamic mode; Donnan membrane technique; screen-printed electrode; free ion concentrations; dynamic mode

Domaines: Chimie

Estelle Ricard, Jose-Paulo Pinheiro, Isabelle Le Hécho, Corinne Parat. ISIDORE, a Probe for In Situ Trace Metal Speciation Based on the Donnan Membrane Technique and Electrochemical Detection Part 2: Cd and Pb Measurements during the Accumulation Time of the Donnan Membrane Technique. Molecules, 2023, 28, pp.846. ⟨10.3390/molecules28020846⟩. ⟨hal-03951327⟩