Measurement of CeO2 Nanoparticles in Natural Waters Using a High Sensitivity, Single Particle ICP-MS

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.

Analytical applications of single particle inductively coupled plasma mass spectrometry: a comprehensive and critical review

“…[234][235][236][237][238] Silver has been monitored in different types of waters, although the most relevant studies are related to the removal of silver containing particles in wastewater treatment plants, [248][249][250][251]254 which has been also the case for Ti-, 251 Zn- 252,253 and Cecontaining particles. 251 In the case of cerium, CeO 2 nanoparticles can be released into the air by diesel emissions being detected in rain water 245 and other natural waters. 38,[243][244][245]247,251 Tap waters have been analysed in relation to the release of incidental nanoparticles containing different metals from copper pipes.…”

“…251 In the case of cerium, CeO 2 nanoparticles can be released into the air by diesel emissions being detected in rain water 245 and other natural waters. 38,[243][244][245]247,251 Tap waters have been analysed in relation to the release of incidental nanoparticles containing different metals from copper pipes. 255,256 Throughfall water from the wash-off of vine leaves treated with Cu-based fungicides has also been analysed by SP-ICP-MS in combination with other techniques to study the mobilization of Cu-containing particles.…”

“…This strategy assumes that engineered nanoparticles are high purity substances, containing a single major element, while natural nanoparticles have heterogeneous multielement compositions. The Ce/La ratio has been reported for identification of CeO 2 nanoparticles, 244,245,247 whereas for TiO 2 nanoparticles, the Ti/Al and Ti/V ratios have been considered. 232,[234][235][236]238,244,247 Whereas SP-ICP-MS with quadrupole instruments is limited to the measurement of two isotopes in an individual particle, TOF instruments are able to record the whole mass spectrum from each particle.…”

“…Both filtration and centrifugation have been used for this purpose, although several authors have reported significant losses of nanoparticles in membrane filters. 126,159,163,245 Thus, filtration should be discouraged unless quantitative recoveries have been proved, therefore settling or centrifugation should be used on a routine basis if removal of large particles is needed.…”

Analysis of Ti- and Pb-based particles in the aqueous environment of Melbourne (Australia) via single particle ICP-MS

“…The performance of ICP-MS can also be improved via sector-field ICP-MS and ICP-MS/MS. While the former may increase mass resolution and as such improve the selectivity and sensitivity especially for interfered isotopes in SP analysis [ 35 ], it is often employed for its higher ion transmission rather than increased mass resolution [ 36 , 37 ]. ICP-MS/MS may be used to exploit chemical affinities and reactions mitigating spectral interferences and improving figures of merit for interfered isotopes [ 38 ].…”