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SINGLE-PARTICLE ICPMS FOR CHARACTERIZING METAL-BASED NANOPARTICLES IN THE ENVIRONMENT - ADVANCES AND CHALLENGES
Citation:
HEITHMAR, E. M. SINGLE-PARTICLE ICPMS FOR CHARACTERIZING METAL-BASED NANOPARTICLES IN THE ENVIRONMENT - ADVANCES AND CHALLENGES. Presented at International Conference on the Environmental Implications and Applications of Nanotechnology, Amherst, MA, June 09 - 11, 2009.
Impact/Purpose:
Presentation
Description:
As engineered metal-based nanomaterials become widely used in consumer and industrial products, the amount of these materials introduced into the environment by a variety of paths will increase. The concentration of metal associated with these engineered nanoparticles will be superimposed on the metal concentration from other natural and anthropogenic nanoparticles of the same or different chemical composition. Therefore, in order to evaluate potential exposure of ecosystems to engineered nanomaterials, methods must be available for measuring spatial and temporal trends in the concentration, size distribution, and metal content of nanoparticles in environmental compartments. Approaches for these types of measurements have been either single-particle methods such as electron microscopy, or ensemble techniques that measure properties of the population of particles. The ensemble methods are less specific than single-particle imaging, but can produce statistically representative characterization of the environmental sample. Ensemble techniques include filtration and ultrafiltration followed by elemental determination by inductively coupled plasma mass spectrometry (ICPMS) to estimate metal concentration in operationally defined size fractions. Hyphenated instrumental techniques, such as flow-field flow fractionation (FFF) coupled with ICPMS, provide better defined size distributions. This presentation describes a third approach, ICPMS in the single particle (SP) mode. SP-ICPMS can provide number density of particles, as well as mass of the measured metal in the particles. It can therefore be used without any accompanying separatory method to screen metal-containing nanoparticle concentrations. Coupled with a size separation method, SPICPMS can provide the fractional metal content of particles, thus discriminating between metal-based nanoparticles and background nanoparticles with only minor metal content (e.g., minerals and metal sorbed on natural organic matter). The theory of SP-ICPMS will be described, and its application as a stand-alone screening method and in combination with size separation will be demonstrated. Current challenges to its wide application in environmental characterization of metal-based nanoparticles, as well as potential solutions to these challenges, will be discussed.