Assessment of microscopy methods for distinguishing engineered nanoparticles from incidental nanoparticles

Recommended Citation Ellickson, Daniel Emick. "Assessment of microscopy methods for distinguishing engineered nanoparticles from incidental nanoparticles." MS O'Shaughnessy for all of his guidance preparing for this project. I would also like to thank Dr. Peters for the use of his laboratory equipment, Jonas Baltrusaitis for microscopy training and advice, and the Heartland Center for financial support for completing this program. iii ABSTRACT The objective of this study was to assess the utility of electron microscopy methods 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 (TiO 2) 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 TiO 2 mixture with ARD displayed the following higher proportions of TiO 2 on the upper stages. TiO 2 /incense samples had very high (79%-90%) TiO 2 proportions, which was not expected since the mixture was 50% TiO 2. Incense particles did not collect with the same efficiency as TiO 2 or ARD, due to their much lower density. Incense particles were entirely carbon based and were not identifiable using TEM/EDS. The TiO 2 /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 TiO 2 mostly alone. Sampling criteria for desired particle loading had to be established in order to obtain usable TEM grids. TiO 2 was distinguishable from all other particles, but accurate particle identity and proportion in samples was not obtainable for combustion particles using these methods.