Monitoring of C^sub 60^ aerosol concentrations during 4-week inhalation study using a carbon aerosol analyzer with adjusted analytical protocol

Fullerenes are interesting carbon nanomaterials with several forms of C^sub 60^, C^sub 70^, C^sub 76^, and more molecules. However, little is known of the risk associated with their exposure. Inhalation is considered the most significant route of exposure to nanoparticles suspended in air, so we need suitable analytical methods of aerosol particles containing the fullerenes. Usually, fullerenes dissolved in organic solvents are analyzed by high performance liquid chromatography (HPLC) technique. For aerosol samples on filters, any extraction process must be conducted before HPLC analysis. In this study, we used a carbon aerosol analyzer for diesel exhaust particulates to determine fullerene amount in aerosol particles without any extraction process. The filter samples were directly analyzed by this instrument within half hour. Our method was applied for aerosols of C^sub 60^ with dispersant, which was sampled from a whole body exposure chamber for rats. Inhalation study was conducted for 4 weeks, 5 days a week, 6 h a day, and one filter sample was obtained from more than 5 h sampling of 6 h exposure. Average concentration of 19 samples of C^sub 60^ aerosols for 4 week inhalation was 0.12 ± 0.03 mg/m^sup 3^ calculated from total aerosol mass and weight fraction of C^sub 60^ and 0.13 ± 0.03 mg/m^sup 3^ measured by the carbon aerosol analyzer. Minimum determination limit of this method was