Identification of platinum nanoparticles in road dust leachate by single particle inductively coupled plasma-mass spectrometry

摘要

AbstractElevated platinum (Pt) concentrations are found in road dust as a result of emissions from catalytic converters in vehicles. This study investigates the occurrence of Pt in road dust collected in Ghent (Belgium) and Gothenburg (Sweden). Total Pt contents, determined by tandem ICP-mass spectrometry (ICP-MS/MS), were in the range of 5 to 79ngg−1, comparable to the Pt content in road dust of other medium-sized cities. Further sample characterization was performed by single particle (sp) ICP-MS following an ultrasonic extraction procedure using stormwater runoff for leaching. The method was found to be suitable for the characterization of Pt nanoparticles in road dust leachates. The extraction was optimized using road dust reference material BCR-723, for which an extraction efficiency of 2.7% was obtained by applying 144kJ of ultrasonic energy. Using this method, between 0.2% and 18% of the Pt present was extracted from road dust samples. spICP-MS analysis revealed that Pt in the leachate is entirely present as nanoparticles of sizes between 9 and 21nm. Although representing only a minor fraction of the total content in road dust, the nanoparticulate Pt leachate is most susceptible to biological uptake and hence most relevant in terms of bioavailability.Graphical abstractDisplay OmittedHighlights•Platinum in road dust of Ghent and Gothenburg is comparable to other medium cities.•Single particle ICP-MS can detect Pt nanoparticles as small as 7.4nm in solution.•Contact with stormwater causes the leaching of small platinum nanoparticles.•With no soluble fraction, Pt is solely present as nanoparticles between 9 and 21nm.•Though a small fraction (3.3%), it is important in terms of bioavailability.