NIOSH recently published a new draft chapter on the analysis of carbon nanotubes and nanofibers on filters to be published in the 5th edition of its Manual of Analytical Methods (NMAM), a collection of methods for sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed. The draft chapter, “Analysis of Carbon Nanotubes and Nanofibers on Mixed Cellulose Ester Filters by Transmission Electron Microscopy,” provides standardized approaches for the analysis of carbon nanoparticles intended to harmonize analytical techniques and allow for the comparison of results between studies. The draft chapter includes guidance on performing transmission electron microscopic analysis on carbon nanotubes and nanofibers that are sampled from occupational atmospheres. The procedures described are based on NIOSH research on the microanalysis of airborne carbonaceous nanomaterials.
The draft chapter is available via the docket on Regulations.gov. Comments on the draft chapter are due by April 28. The 5th edition of NMAM, released in May 2016, is the first electronic-only version of the publication. It includes six new biomonitoring methods as well as new or updated chapters on factors affecting aerosol sampling, measurement of fibers, monitoring diesel particulate exhaust in the workplace, and other topics.
NIOSH has developed and evaluated more than 300 methods that are included in NMAM. The agency recommends that the best available method be used for making each measurement, and recognizes that methods published by others (OSHA, MSHA, and EPA, for example) may have advantages over NIOSH methods, depending on the sampling situation. According to NIOSH, an industrial hygienist should determine the sampling protocol, taking into consideration analytical accuracy, cost, and optimum sampling number.