Development of an analytical technique for the determination of occupational exposures to airborne carbon nanotubes

This research was conducted to develop an analytical technique that can provide data regarding the physical and chemical characteristics of airborne carbon nanotubes (CNTs) and their agglomerates. There is presently no single standard technique or methodology to that can provide this data. Existing analytical instruments and analytical techniques for evaluating nanoparticle concentrations cannot simultaneously provide morphology, state of agglomeration, surface area, mass, size distribution and chemical composition data critical to making occupational health assessments for exposures to CNTs. This research utilized scanning scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA) to assess the morphology, mass and chemical composition of CNTs collected using various commercial sample filters. Individual CNTs were found to readily agglomerate at or in the face of these filters with diameters ranging from 1 – 63 um. This research also investigated and established CNT deposition in these filters. Deposition was uneven in each of the researched filters. It illustrated that a sufficient mass for CNT analysis by TGA is not common under most current research and production uses of CNTs. This research resulted with a number of observations and recommendations of benefit to the scientific community that includes: challenges stemming from analysis, CNT behaviors, and the appropriateness of commonly available instruments and techniques for the measurement of airborne CNTs. The research data and observations were assessed and used to develop an analytical technique to measure airborne CNTs at a 10 nm resolution and 1 ug/m3 mass limit of detection.