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The emission of Platinum-group elements (PGE) from automobile catalytic converters has led to rapid increases in Pt, Pd and Rh concentrations in roadside media. This paper examines the temporal variability of PGE levels in road dusts and roadside soils on a seasonal basis over a 12 month period. Road dust and roadside soil samples were analysed by ICP-MS following microwave digestion and cation exchange. Concentrations of PGE in all road dust and roadside soil samples are elevated above local background concentrations with maximum levels of Pt − 440 ng g −1 , Rh − 91 ng g −1 and Pd − 440 ng g −1 . Systematic seasonal variations in PGE levels are observed in both sample types and the temporal distribution of PGE levels is affected by a number of factors including surface morphology and rainfall. PGE ratios in road dusts and soils are consistent with known catalytic converter composition throughout the sampling period indicating the PGE remain associated during mobilisation and transport.

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The accurate determination of Pt, Pd and Rh (platinum group elements, PGE) in environmental samples by inductively coupled plasma–mass spectrometry (ICP-MS) is complicated by molecular ion and doubly charged ion interferences (e.g. CuAr+, HfO+, SrO+, YO+ and Pb2+). Two matrix separation techniques, tellurium coprecipitation and ion exchange, are compared in terms of PGE recovery and separation efficiency by application to standard solutions and the new reference material BCR-723, a road dust material collected from the Tanzenberg Tunnel in Austria. Ion exchange using Dowex AG50W-X8 strong cation exchange resin is highly effective in terms of both separation efficiency (>99.7%) and PGE recovery (93.8 to 101.6%) and allows accurate, interference-free determination of PGEs. PGE recoveries by Te coprecipitation are incomplete, ranging between 84 and 93%. Significant amounts of copper (up to c. 30%) are also recovered, which, due to CuAr + formation, causes interferences on both 103 Rh (monoisotopic) and 105 Pd. The generally high levels of interferent elements in environmental matrices (e.g. Cu, Pb etc.) and the magnitude of Cu recovery by Te coprecipitation limit the applicability of data correction using interference equations. Reductions in Cu yield by Te coprecipitation, to <4%, can be achieved through the addition of potassium iodide prior to matrix separation. However, due to the incomplete recovery of PGEs, ion exchange provides a more robust method for the determination of low levels of PGEs.