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Quantifying silica in filter-deposited mine dusts using infrared spectra and partial least squares regression.

Authors
Weakley-AT; Miller-AL; Griffiths-PR; Bayman-SJ
Source
Anal Bioanal Chem 2014 Jul; 406(19):4715-4724
NIOSHTIC No.
20044528
Abstract
The feasibility of measuring airborne crystalline silica (alpha-quartz) in noncoal mine dusts using a direct-on-filter method of analysis is demonstrated. Respirable a-quartz was quantified by applying a partial least squares (PLS) regression to the infrared transmission spectra of mine-dust samples deposited on porous polymeric filters. This direct-on-filter method deviates from the current regulatory determination of respirable a-quartz by refraining from ashing the sampling filter and redepositing the analyte prior to quantification using either infrared spectrometry for coal mines or x-ray diffraction (XRD) from noncoal mines. Since XRD is not field portable, this study evaluated the efficacy of Fourier transform infrared spectrometry for silica determination in noncoal mine dusts. PLS regressions were performed using select regions of the spectra from nonashed samples with important wavenumbers selected using a novel modification to the Monte Carlo unimportant variable elimination procedure. Wavenumber selection helped to improve PLS prediction, reduce the number of required PLS factors, and identify additional silica bands distinct from those currently used in regulatory enforcement. PLS regression appeared robust against the influence of residual filter and extraneous mineral absorptions while outperforming ordinary least squares calibration. These results support the quantification of respirable silica in noncoal mines using field-portable infrared spectrometers.
Keywords
Mining-industry; Silica-dusts; Mathematical-models; Measurement-equipment; Analytical-methods; Analytical-instruments; Dust-measurement; Dust-particles; Quartz-dust; Respirable-dust; Airborne-dusts; Porous-materials; Filters; Sample-preparation; Sampling; Sampling-equipment; Sampling-methods; Infrared-spectroscopy; X-ray-analysis; Author Keywords: Partial least squares; Monte Carlo unimportant variable elimination; Silica measurement; FT-IR; Mine dust
Contact
A. T. Weakley , Department of Chemical and Materials Engineering, University of Idaho, PO Box 441021, Moscow, ID 83844-1021, USA
CODEN
ABCNBP
CAS No.
14808-60-7
Publication Date
20140701
Document Type
Journal Article
Email Address
aweakley@vandals.uidaho.edu
Fiscal Year
2014
NTIS Accession No.
NTIS Price
Identifying No.
M062014
Issue of Publication
19
ISSN
1618-2642
NIOSH Division
OMSHR
Priority Area
Mining
Source Name
Analytical and Bioanalytical Chemistry
State
ID; WA; UT
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