Applications of Single Particle ICPMS in Detection and Quantification of Engineered Nanomaterials

Wednesday, September 4, 2013

4:00 pm


Robert Reed

Robert Reed
Postdoctoral Candidateat
Colorado School of Mines
Department of Chemistry and Geochemistry.

Abstract: Increased production and use of engineered nanoparticles (NPs) suggests increased potential for release to the environment. Although studies quantifying human exposure to NPs are scarce, it is likely that increased industrial production will lead to human contact and NP exposure (1). Toxicity of NPs is typically found to be greater than that of corresponding larger (i.e. micron+ sized) particles in in vivo and in vitro tests (2, 3), providing motivation to develop analytical methods for detection and quantification of these materials. Predicted soil and surface water concentrations resulting from use of these materials, obtained from life cycle assessments, are generally in the part-per-trillion range (4, 5). Techniques which are commonly applied to NP analysis such as electron microscopy and dynamic light scattering are not capable of simultaneous detection and quantification of these particles at such low concentrations.

Single particle inductively coupled plasma mass spectrometry (spICPMS) is a relatively new approach for detecting NPs in aqueous solutions. It was developed for detection of natural and engineered colloids (6, 7) and has been used recently for analysis of metal-containing NPs such as Ag, ZnO, TiO2, and CeO2 (8-11). In this seminar data are presented on the use of spICPMS for a variety of applications with relevance to environmental and toxicity studies.

Analysis of carbon nanotubes (CNTs) in the environment is challenging due to the interfering natural carbon background. One potential method for detection of CNTs is to use spICPMS to detect residual catalyst metal nanoparticles as proxies for the CNTs themselves. Several brands of CNT were shown to be detectable by spICPMS monitoring for metals such as Co, Mo, and Y. Release of CNTs from a polymer nanocomposite placed in water for one week was found to scale with mass loading concentration.

Microliter volumes of Daphnia magna hemolymph were extracted from test animals after exposure to either dissolved Ag or Ag nanowires. Quantification of dissolved and particulate Ag mass concentrations in hemolymph, as well as particle number concentrations, was performed using spICPMS. Imaging of hemolymph by SEM confirmed the presence of both Ag nanowires and silver-rich precipitates within Daphnia magna.

The Alte Donau lake in Vienna, Austria, receives an estimated 1,000,000 bathers per summer season. This makes it an ideal location to test for the potential release and persistence of nano-TiO2 used in sunscreens. Surface water collected year-round from the lake was analyzed for Ti by spICPMS, with Ti-containing particle number concentrations increasing by up to a factor of 8 during the period July-September. This complements bulk chemistry data performed by ICP-OES, which shows an increase in the Ti/Al ratio during the summer bathing season.