Primary Particle Size Distribution Measurement of Nanomaterials by Using TEM

Industrial applications of nano-particles are reported in many fields recently. Regulation of nano-materials is also discussed in Organization for Economic Co-operation and Development (OECD). European Union (EU) announced the definition of nano-material in 2012. According to EU definition, nanomaterial means a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm – 100 nm. They also announced that particle size should be considered the primary particles in agglomerates or aggregates. For regulatory purposes, it is necessary to measure the size distribution of nano-particles based on the number concentration. European Food Safety Authority (EFSA) recommended using at least two different analytical methods to identify nano-materials for this EU regulation, and one of which should be electron microscopy [1]. Transmission electron microscope (TEM) is the most useful techniques that can give precise information on shape and size of the primary nanoparticles. In this study, for the regulatory use of particle size measurement by TEM, a primary particle size distribution of nano-particles by TEM was performed, and the counted particle number was statistically examined.