Development of both documentary standards and reference materials is essential for nanotechnology stakeholders: researchers, who need to calibrate or verify their measuring instruments; industry, who must compete with their products in national and international markets and comply with relevant regulations; governments, who need to provide or interpret regulatory requirements; and consumers, who would like to know what their products contain.
In this study, we summarise recent contributions made by the National Measurement Institute (NMI) to the development of a certified titanium dioxide nano-rod reference material; ERM FD103. We also discuss NMI’s participation in work carried out in both the Versailles project on Advanced Materials and Standards (VAMAS) and Technical Committee 229 “Nanotechnologies” of the International Organization for Standardization (ISO), which aims to develop validated protocols for the measurement of primary particle size distributions by transmission electron microscopy (TEM) and will lead to a corresponding ISO standard. NMI’s involvement here has focused on silica (analysed using TEM and atomic force microscopy as well as several ensemble techniques), gold nanorods and titania samples [1] (TEM analysis only).
We discuss the challenge of measuring the dimensional properties of many thousands of individual particles to achieve statistical relevance, the influence of image analysis parameters and their effects on the measurement uncertainty, and the challenges of measuring non-spherical particles. We discuss the issue of method divergence, i.e., differences in measurement results between different measurement techniques measurement of complex shape descriptors and provide insight into measurement uncertainty contributions arising from a number of different influence factors.
[1] Grulke EA et al, Size and shape distributions of primary crystallites in titania aggregates, Adv Powder Technol 28:1647–1659 (2017)