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Characterizing Concentrations and Size Distributions of Metal-Containing Nanoparticles in Waste Water
Citation:
HEITHMAR, E. M. AND S. Pergantis. Characterizing Concentrations and Size Distributions of Metal-Containing Nanoparticles in Waste Water. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-10/117, 2010.
Impact/Purpose:
The use of ENMs in consumer, industrial, and agricultural products, as well as in environmental technology is rapidly increasing (Ponder, Darab et al. 2001; Chaudhry, Scotter et al. 2008; Nanotechnologies 2010). This is largely due to the unique optical, electrical, and chemical properties of nano-scale particles. Often, the benefit of using nanomaterials stems from the increased surface area per unit mass of material, which increases with the inverse of the diameter in the case of spherical particles. This results in faster rates of chemical reactions such as oxidative catalysis that occur at surfaces. Sometimes the benefit of nanomaterials arises from the quantum nature of energy states at the nanometer scale, as in the wavelength tuning of the fluorescence of quantum dots (Michalet, Pinaud et al. 2005). In the health sciences, the ability of ENMs to bind to cell walls can be utilized for drug delivery (Lai, Trewyn et al. 2003; Zhang, Pornpattananangkul et al. 2010).
Description:
Nanomaterials containing metals are finding increasing use in consumer, industrial, and medical products, and they are subsequently being released into the environment. Methods for detecting, quantifying, and characterizing these materials in complex matrices are critical for the eventual understanding of their implications to environmental quality and human health. This report describes recent progress in the development of new metrology tools. Single particle – inductively coupled plasma mass spectrometry (SP-ICPMS) is used to analyze complex aqueous samples. SP-ICPMS simultaneously quantifies the concentration of nanoparticles containing an analyte metal and measures the metal mass in individual nanoparticles. The accuracy of SPICPMS is assessed over a range of nanoparticle sizes. The utility of the technique in a number of applications is examined. Nanoparticles containing the analyte element can be measured accurately and precisely in the presence of a 10,000-fold greater concentration of other nanoparticles. SP-ICPMS is used to assess transformation of nanoparticles induced by changes in ionic strength. A screening-level assessment of metal-containing nanoparticles in urban runoff using SP-ICPMS is demonstrated, and preliminary studies of coupling SP-ICPMS with online nanoparticle size separation methods are presented.