Selective determination of Pd nanostructures in environmental matrices - Application of a carbon monoxide probe

The use of metallic platinum group metals (PGMs) increased the content of these metals in various elements of the environment. They undergo changes in the environment, become bioavailable and mobile and therefore dangerous. It is important to collect information not only about the total content of PGMs, but also about their chemical forms (which differ in eco-toxicity). Method based on quantification of CO adsorption on the surface of metallic Pd can be used for determination of its nanoparticles in water and plant tissue. It is highly reproducible (repeatability 2%) and not sensitive to the matrix effect (repeatability 10% in unprocessed plant extract). The limit of detection (LOD) equals 4.5 µg Pd-NPs, and can be easily lowered after reduction of the sample volume by evaporation. Adding low-temperature ultrasound-assisted dissolution of the sample in conc. nitric acid allows to distinguish Pd-NPs from Pt-NPs, but only if the contribution of Pd in the adsorption of carbon monoxide is higher than 7.5%.