Date of Degree
MS (Master of Science)
Occupational and Environmental Health
The objective of this study was to assess the utility of electron microscopy for the purpose of distinguishing engineered nanoparticles from "incidental" nanoparticles. Methods included the use of transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) to analyze samples of known ratios of titanium dioxide (TiO2) to Arizona road dust (ARD) or incense particles. TEM collection methods were analyzed for two different samplers: a Marple impactor and an electro-static precipitator (ESP). TEM grids were placed on the four lowest stages of the impactor. Results for impactor stages of a 10:1 ratio of TiO2/ARD mixture displayed the following percentages TiO2: 44%, 44%, 83%, and 90%. TiO2/incense samples had very high (79%-90%) TiO2 proportions, which was not expected since the ratio was 1:1. These combustion particles did not collect with the same efficiency as TiO2 or ARD. In conclusion, incense particles were entirely carbon based and were not identifiable using TEM/EDS. The TiO2/ARD mixture demonstrated that the impactor would remove most of the larger particles so that grids on the filter stage could be used to analyze and image TiO2 mostly alone. Sampling criteria for desired particle loading had to be established in order to obtain usable TEM grids. TiO2 was distinguishable from all other particles, but accurate particle identity and proportion in samples was not obtainable for combustion particles using these methods.
Copyright 2011 Daniel Ellickson
Ellickson, Daniel Emick. "Assessment of microscopy methods for distinguishing engineered nanoparticles from incidental nanoparticles." master's thesis, University of Iowa, 2011.