A novel flow-injection method for simultaneous measurement of platinum (Pt), palladium (Pd) and rhodium (Rh) in aqueous soil extracts of contaminated soil by ICP-OES

Abstract

Abrasion of modern car catalytic converters has resulted in increased deposition of anthropogenic platinum group elements (PGEs; Pd, Pt, Rh) in roadside soils, but still little is known about their solubility, bioavailability and reaction with the soil solid phase. As the extremely low PGE concentrations along with matrix interactions represent a major analytical limitation for studying the fate of PGEs in soils, we propose an advanced flow-injection (FI) system for measuring Pd, Pt and Rh within the same analysis using inductively coupled plasma-optical emission spectrometry (ICP-OES). A combined set of alumina micro-columns along with optimised eluents was employed for concurrent separation of disturbing cations and analyte enrichment to minimise interferences and improve the limits of detection (LOD) by a factor of 5 to 10 compared to conventional measurements, with satisfactory relative standard deviations (RSD) of 2–7%. The method proved to be suitable for simultaneous measurements of PGEs in weak soil extracts of contaminated soil representing potentially bioavailable fractions and sorption envelopes, providing information about the interaction of PGEs with the soil solid phase. The method offers new opportunities to explore the fate of PGEs in soils and similar environmental samples.