Abstract
As the production and use of cerium oxide nanoparticles (CeO2 NPs) increases, so does the concern of the scientific community over their release into the environment. Single particle inductively coupled plasma mass spectrometry is emerging as one of the best techniques for NP detection and quantification; however, it is often limited by high size detection limits (SDL). To that end, a high sensitivity sector field ICP-MS (SF-ICP-MS) with microsecond dwell times (50 µs) was used to lower the SDL of CeO2 NPs to below 4.0 nm. Ag and Au NPs were also analyzed for reference. SF-ICP-MS was then used to detect CeO2 NPs in a Montreal rainwater at a concentration of (2.2 ± 0.1) × 108 L−1 with a mean diameter of 10.8 ± 0.2 nm; and in a St. Lawrence River water at a concentration of ((1.6 ± 0.3) × 109 L−1) with a higher mean diameter (21.9 ± 0.8 nm). SF-ICP-MS and single particle time of flight ICP-MS on Ce and La indicated that 36% of the Ce-containing NPs detected in Montreal rainwater were engineered Ce NPs.
Highlights
Due to their unique properties, engineered nanomaterials are widely used in numerous commercial products
CeO2 NPs in Milli-Q water, with or without dissolved Ce. While both spike intensity and background signal decreased as dwell time was decreased from 500 to 20 μs (Figure S1), S/N was clearly improved at the shorter dwell times (Figure 1)
The lowest size detection limits (SDL) was measured with a 20 μs dwell time, it was not used further here since analysis was limited to one million datapoints per run
Summary
Due to their unique properties, engineered nanomaterials are widely used in numerous commercial products. Cerium oxide (CeO2 ) nanoparticles (NPs) are among the most commonly used engineered NPs, with applications in catalysis [1,2,3], the manufacturing of semiconductors [2], biomedicine [4] and agriculture [5], among other fields. They are commonly found as UV filters in sunscreens, additives in diesel fuels and as a component of paints and stains [6,7]. This is mainly because the direct analysis of CeO2 NPs in the environment is extremely challenging due to their small sizes
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