Voltammetric and spectroscopic methods for the ruthenium determination in the environment at ultra-trace concentration level: critical comparison and application to airborne particulate matter, vegetables, superficial waters, mussels, clams and soils

The problem related to the presence of Platinum Group Metals (PGMs) in the environment has raised much attention and great interest in the scientific community. This is due to the fact that the PGMs are widely used in various fields, such as anticancer drugs, jewels production, photographic operations, industrial catalysts, and especially autocatalytic converters. In the last case, their continuous use and deterioration implies a considerable release of these metals in the environment. It should be noted that the metals initially used in autocatalytic converters were platinum, palladium and rhodium, but in recent years such PGMs were gradually and partially replaced, or alloyed with osmium and especially ruthenium. Their addition in the manufacture of autocatalytic converters helps them withstand high temperatures and wear, thus increasing the product life. Thus, the increasing use of autocatalytic converters shows two decidedly conflictual effects on the environment: an evident and drastic reduction of the concentration levels of lead, and, at the same time, an equally evident and widespread increase of the PGMs concentration, and in particular of ruthenium, due to its increasing use in recent years. This work proposes a voltammetric method for the determination of ultra-trace ruthenium in environmental samples: airborne particulate matter, vegetables, superficial waters, mussels, clams and soils/sediments. To better validate the proposed analytical procedure, a critical comparison with spectroscopic measurements - electrothermal atomic absorption spectroscopy (ET- AAS) because of its well established and tested robustness - has been also carried out and discussed here. All the parameters of interest for the set-up of an analytical method, such as trueness and precision (accuracy), limit of detection and quantification, selectivity and, especially, sensitivity were taken into account