OSMIUM, AN EMERGING ANTHROPIC POLLUTING TRAFFIC-RELATED METAL. ANALYTICAL METHODS FOR ITS DETERMINATION IN ENVIRONMENTAL MATRICES OF INTEREST FOR HUMAN HEALTH AND INVOLVED IN THE FOOD CHAIN

In the environmental field and in the last decade, the scientific attention has been addressed to platinum group metals (PGMs) owing to their increasing concentration in all the environmental matrices. This is due to the increasing use of these metals in several fields as for example production of industrial catalysts, anticancer drugs, jewels, even if in any case the cause of their growing concentrations in the environment is consequence of the compelling employment of autocatalytic converters. In fact the incorrect use “stop and go” of these converters, with consequent deterioration and abrasion, certainly implies a considerable release in the environment of airborne particulate matter at high PGMs concentration, which results to be the greatest, if not the only, source of contamination of the various environmental matrices, i.e. superficial water, soils, sediments, vegetables and so on. Really, after the first massive use of platinum, palladium and rhodium in the production of autocatalytic converters, there has been a gradual reduction of these PGMs with consequent growing use of iridium, ruthenium and, especially, osmium. Indeed, in the last decade, and more and more frequently, osmium together with iridium has been employed as alloying with platinum, palladium and rhodium in the manufacturing of autocatalytic converters in order to withstand high temperature and high wear. In fact, osmium in particular is rarely used in its pure state, and it is instead considered an important alloying agent especially in high-wear applications, owing to its strong corrosion resistance even at very high temperatures. Thus, this work intends to propose voltammetric methods for the osmium determination at ultra-trace level concentration in environmental samples: airborne particulate matter, superficial waters, soils/sediments, vegetables, mussels, clams and algae. To better validate the proposed analytical procedures, a critical comparison with spectroscopic measurements — electro-thermal atomic absorption spectroscopy (ET–AAS) because of its well established and tested robustness — has been also carried out and discussed here, taking into account all the parameters of interest to set-up an analytical method, such as precision and trueness (that together give accuracy), limit of detection and quantification, selectivity and, especially, sensitivity.