PRE-CONCENTRATION STRATEGIES FOR DETERMINING RARE-EARTH ELEMENTS IN MARINE TETRAPOD LIVERS

Abstract

Coastal ecosystems are vulnerable to the influx and deposition of contaminating effluents driven by human activities, putting an entire ecological niche at risk, as well as the health of this biota. This fact is even more concerning in cases where potential environmental contaminants are not regulated by physiological processes, particularly for marine tetrapods, accumulating in their organisms and moving through the trophic levels of the food chain.In this context, rare earth elements (REEs) are found in different concentrations in the environment. Furthermore, its large-scale applications through anthropogenic activities result in its uncontrolled dumping in coastal environments, with great potential for contamination of biota. Analytical methods for determining REEs in biological material are still under development, with the acid digestion procedure, followed by determination by inductively coupled plasma mass spectrometry (ICP-MS) being the most used. However, when it comes to determining elements at extremely low concentrations using ICP-MS, such as REEs, a pre-concentration step is often required to achieve more robust quantification limits. This project aims to develop a pre-concentration method, based on solid phase removal (SPE), to determine REEs. Thus, at least two sorbents will be evaluated: 1) Chelex-100 resin, as it is the most used sorbent for the concentration of REEs in environmental samples; 2) a new sorbent, hitherto little explored, based on the immobilization of carminic acid on the XAD-16 resin. In principle, batch procedures will be used to conduct the SPE, in sequence, depending on the progress of the project, "off-line" and "on-line" procedures will be evaluated in columns and associated with the ICP-MS.