Quantitative analysis and characterization of PtNPs in road dust based on ultrasonic probe assisted extraction and single particle inductively coupled plasma mass spectrometry

Abstract

As a result of their growing use, platinum nanoparticles (PtNPs) can pollute different environmental compartments, especially road dust due to their application in vehicle catalytic converters. Their presence in these matrices should be controlled to achieve adequate environmental risk assessment, but there is a lack of standardized analytical methods for this purpose. Therefore, this study describes the development and analytical characterization of a rapid sample preparation strategy for the analysis of PtNPs in road dust by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). Parameters within the critical steps of the extraction (such as the type of energy, sample-to-reagent ratio, intensity, or time), and subsequent phase separation have been optimized using a road dust reference material (BCR-723, certified for total Pt), and spiked road dust samples. The final method consists of a sonication probe assisted extraction, using water as extractant, followed by a separation based on centrifugation, and dilution prior to SP-ICP-MS. Information about size and both mass- and particle-based concentration is provided in <11 min. A recovery rate of 100 ± 1% is achieved in the spiked road dust samples, and a 12 ± 1% (n = 6) of the total Pt was found to be as PtNPs in the certified reference material. The applicability of this methodology has been proven performing the analysis of PtNPs in real road dust samples, with sizes between 15 and 75 nm, and concentrations (6.0–20.0 ng g−1) that represents from 11 to 27% of the Pt content.