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Multi-walled carbon nanotubes: sampling criteria and aerosol characterization.
MedLine Citation:
PMID:  23033994     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
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 µm(2) filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT's, resuspended at a concentration of 10 mg/m(3), contained 2.7 × 10(4) particles/cm(3). Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9 × 10(5) nanotubes/cm(3). In addition, fibrous particles within the aerosol had a count median length of 3.04 µm and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 µm. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 µm. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88 g/cm(3), 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.
Authors:
Bean T Chen; Diane Schwegler-Berry; Walter McKinney; Samuel Stone; Jared L Cumpston; Sherri Friend; Dale W Porter; Vincent Castranova; David G Frazer
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Inhalation toxicology     Volume:  24     ISSN:  1091-7691     ISO Abbreviation:  Inhal Toxicol     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-04     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8910739     Medline TA:  Inhal Toxicol     Country:  England    
Other Details:
Languages:  eng     Pagination:  798-820     Citation Subset:  IM    
Affiliation:
Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown, WV , USA.
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