Encarna Companys Ferran

The nutritional or toxic impact of heavy metals is related to the distribution of these elements among different species. Although spectrometric techniques are highly developed for determining the concentration of total elements in multi-metal systems, a more rigorous approach requires analytical techniques capable of determining the bioavailability and the 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), capable of directly measuring the free concentration of the sample, without the need for any prior treatment. We have applied AGNES to the determination of free metal concentrations in seawater, estuary and river water, soil extracts, nanoparticle systems and also in an alcoholic beverage, wine. AGNES has been widely applied to the determination of free Zn, Cd and Pb. We are now working on the determination of In, Cu, Sn and Sb with new designs and strategies. We are also working on the application of another technique, the Donnan membrane technique (DMT), for the determination of free concentration in different matrices. The wide range of elements that can be determined simultaneously in a sample is a great advantage, while long analysis times limit its applicability. We are focusing on applying various strategies to make it a promising technique for the analysis of metal speciation in natural samples, including in situ measurements.