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Multi-walled carbon nanotubes: sampling criteria and aerosol characterization.

Authors
Chen-BT; Schwegler-Berry-D; McKinney-W; Stone-S; Cumpston-JL; Friend-S; Porter-DW; Castranova-V; Frazer-DG
Source
Inhal Toxicol 2012 Oct; 24(12):798-820
NIOSHTIC No.
20041623
Abstract
This study intends to develop protocols for sampling and characterizing multi-walled carbon nanotube (MWCNT) aerosols in workplaces or during inhalation studies. Manufactured dry powder containing MWCNT's, combined with soot and metal catalysts, form complex morphologies and diverse shapes. The aerosols, examined in this study, were produced using an acoustical generator. Representative samples were collected from an exposure chamber using filters and a cascade impactor for microscopic and gravimetric analyses. Results from filters showed that a density of 0.008-0.10 particles per m2 filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT's, resuspended at a concentration of 10 mg/m3, contained 2.7104 particles/cm3. Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9105 nanotubes/cm3. In addition, fibrous particles within the aerosol had a count median length of 3.04 m and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 m. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 m. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88g/cm3, and the mean shape factor of individual nanotubes was between 1.94 and 2.71. The information obtained from this study can be used for designing animal inhalation exposure studies and adopted as guidance for sampling and characterizing MWCNT aerosols in workplaces. The measurement scheme should be relevant for any carbon nanotube aerosol.
Keywords
Sampling; Aerosols; Aerosol-particles; Particulate-dust; Particulates; Exposure-levels; Filters; Analytical-methods; Microscopic-analysis; Gravimetric-analysis; Animal-studies; Inhalation-studies; Inhalants; Author Keywords: Multi-walled carbon nanotubes; engineered nanoparticles; characterization; inhalation studies; exposure assessment method
Contact
Bean T. Chen, Ph.D., Pathology and Physiology Research Branch, Mailstop L-2015, NIOSH-CDC, 1095 Willowdale Road, Morgantown, WV 26505-2888
CODEN
INHTE5
Publication Date
20121001
Document Type
Journal Article
Email Address
bdc4@cdc.gov
Fiscal Year
2013
NTIS Accession No.
NTIS Price
Identifying No.
B10242012
Issue of Publication
12
ISSN
0895-8378
NIOSH Division
HELD
Priority Area
Construction; Manufacturing
Source Name
Inhalation Toxicology
State
WV
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