Accumulation of Mg to Diffusive Gradients in Thin Films (DGT) devices: Kinetic and thermodynamic effects of the ionic strength
Altier Infantes, Alexandra
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Availability of magnesium is a matter of concern due to its role in many environmental and biological processes. Diffusive Gradients in Thin Films (DGT) devices can measure Mg availability in situ. This work shows that Mg accumulation in water largely increases when ionic strength (I) decreases. This phenomenon can be explained from (i) the increase of both the association equilibrium (K) and rate (ka,R) constants for the reaction between Mg cations and resin sites, and (ii) the growing contribution of the partitioning of Mg cations at the resin–gel interface, as I decreases. Two theoretical models that take into account electrical interactions among Mg cations, background electrolyte, and resin sites can successfully be used to determine ka,R and K at each I. Both models yield similar ka,R values, which fulfill an expression for the kinetic salt effect. For freshwater (with a typical salinity of 10 mM and circumneutral pH), the binding of Mg is so fast and strong that the simplest perfect-sink DGT expression can be helpful to predict (overestimation lower than 5%) the accumulation in solutions with Mg concentrations up to 1 mM whenever the deployment time is below 9 h. Perfect sink conditions can still be applied for longer times, in systems with either a lower I or a lower Mg concentration.
Is part ofAnalytical Chemistry, 2016, vol. 88, núm. 20, p. 10245-10251
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Extending the use of Diffusive Gradients in Thin Films (DGT) to solutions where competition, saturation, and kinetic effects are not negligible Jiménez-Piedrahita, Martín; Altier Infantes, Alexandra; Cecilia Averós, Joan; Puy Llorens, Jaume; Galceran i Nogués, Josep; Rey Castro, Carlos; Zhang, Hao; Davison, William (American Chemical Society, 2017-06-20)DGT (Diffusion Gradients in Thin films) was designed to sample trace metals in situ at their natural concentrations. The setup and the experimental deployment conditions were established to allow interpretation of a linear ...
Altier Infantes, Alexandra; Jiménez-Piedrahita, Martín; Uribe Kaffure, Ramiro; Rey Castro, Carlos; Cecilia Averós, Joan; Galceran i Nogués, Josep; Puy Llorens, Jaume (CSIRO Publishing, 2018)Natural waters contain mixtures of ligands, which collectively affect the availability of trace metals. The individual contribution of each complex to the overall metal flux received by a sensor can be described in terms ...
Jiménez-Piedrahita, Martín; Altier Infantes, Alexandra; Cecilia Averós, Joan; Rey Castro, Carlos; Galceran i Nogués, Josep; Puy Llorens, Jaume (Elsevier, 2015-05-02)Binding resin beads used in DGT (Diffusion Gradients in Thin films) tend to settle to one side of the resin during casting. This phenomenon might be relevant for metal accumulation when partially labile complexes dominate ...