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Quantitative analysis of unique deposition pattern of submicron Fe3O4 particles using computer-controlled scanning electron microscopy.

Authors
Jaques-PA; Hopke-PK; Gao-P
Source
Aerosol Sci Tech 2012 Aug; 46(8):905-912
NIOSHTIC No.
20040714
Abstract
This study was designed to optimize particle counting of a unique deposition pattern of iron oxide (Fe3O4) particles that were collected by a multidomain magnetic passive aerosol sampler (MPAS). Fe3O4 is paramagnetic with a high magnetic susceptibility, rendering high collection efficiencies. The MPAS was designed exclusively for measuring particle penetration through protective clothing. To quantify particle deposition by size, two counting methods were employed with a computer-controlled scanning electron microscope (CCSEM). Based on a sequential set of measurements at known coordinates, particles were quantified across particle clusters collected by individual magnets. Because all magnets were of equal dimensions and strength, the particle concentration per cluster across the entire MPAS substrate was expected to be relatively uniform. However, since individual CCSEM fields are extremely small compared with the full sample, a randomized counting approach was used to determine how many fields were needed to obtain a representative subsample. Results by the sequential method show that particle numbers were higher toward the edge of the cluster, dominated by smaller particles; moderate at the center, dominated by larger particles; and null at the corners. The results additionally show that counting by the random method was comparable with the sequential method and repeatable for particle counts ranging from 3 to 383 particles per field, or 409,565-52,287,826 particles per substrate, taking between 25 and 53 min, respectively. The results suggest that with the random method, the CCSEM provided a powerful tool for quantitative analyses of particle numbers with unique deposition patterns.
Keywords
Particulate-dust; Particulates; Iron-oxides; Aerosols; Aerosol-particles; Aerosol-sampling; Magnetic-properties; Measurement-equipment; Iron-oxides; Nanotechnology; Quantitative-analysis
Contact
Pengfei Gao, National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health, 626 Cochrans Mill Road, Pittsburgh, PA 15236,
CODEN
ASTYDQ
CAS No.
1345-25-1
Publication Date
20120801
Document Type
Journal Article
Email Address
PGao@cdc.gov
Fiscal Year
2012
NTIS Accession No.
NTIS Price
Identifying No.
B05102012
Issue of Publication
8
ISSN
0278-6826
NIOSH Division
NPPTL
Priority Area
Manufacturing; Public Safety
Source Name
Aerosol Science and Technology
State
PA; NY
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