Associate Professor, University of Lleida
The nutritional or toxic impact of heavy metals is linked to the distribution of this element amongst a set of the different species. Although spectrometric techniques are well developed for the total element concentration determination in the multimetal systems, a more rigorous approach requires analytical techniques able to determine bioavailability, free and labile fractions of the total element present in the sample.
In our research group, we have developed a new electroanalytical technique: AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) able to measure directly, without the need of any pretreatment, the free concentration in the sample. We have applied AGNES to the determination of free metal concentration in sea, estuarine and river water, soil extracts, systems with nanoparticles and also in an alcoholic beverage, wine. AGNES has been extensively applied to the determination of free Zn, Cd and Pb. We are dealing now with the determination of In, Cu, Sn and Sb with new designs and strategies.
We are also dealing with the application of another technique, the Donnan Membrane Technique
(DMT) to the determination of free concentration in different media. The broad spectrum of elements that can be simultaneously determined in a sample is a great advantage, while the long times limits its applicability. We are focussing on the application of different strategies to render it as a promising technique for metal speciation analysis of natural samples also for in situ measurements.