title: Evaluation of Diffuse Reflection Infrared Spectrometry for End-of-Shift Measurement of α-quartz in Coal Dust Samples.
abstract: The inhalation of toxic substances is a major threat to the health of miners, and dust containing respirable crystalline silica (α-quartz) is of particular concern, due to the recent rise in cases of coal workers' pneumoconiosis and silicosis in some U.S. mining regions. Currently, there is no field-portable instrument that can measure airborne α-quartz and give miners timely feedback on their exposure. The U.S. National Institute for Occupational Safety and Health (NIOSH) is therefore conducting studies to investigate technologies capable of end-of-shift or real-time measurement of airborne quartz. The present study focuses on the potential application of Fourier transform infrared (FT-IR) spectrometry conducted in the diffuse reflection (DR) mode as a technique for measuring α-quartz in respirable mine dust. A DR accessory was used to analyze lab-generated respirable samples of Min-U-Sil 5 (which contains more than 90% α-quartz) and coal dust, at mass loadings in the ranges of 100-600 μg and 600-5300 μg, respectively. The dust samples were deposited onto three different types of filters, borosilicate fiberglass, nylon, and polyvinyl chloride (PVC). The reflectance, R, was calculated by the ratio of a blank filter and a filter with deposited mine dust. Results suggest that for coal and pure quartz dusts deposited on 37 mm PVC filters, measurements of -log R correlate linearly with known amounts of quartz on filters, with R(2) values of approximately 0.99 and 0.94, respectively, for samples loaded up to ∼4000 μg. Additional tests were conducted to measure quartz in coal dusts deposited onto the borosilicate fiberglass and nylon filter media used in the NIOSH-developed Personal Dust Monitor (PDM). The nylon filter was shown to be amenable to DR analysis, but quantification of quartz is more accurate when the filter is "free," as opposed to being mounted in the PDM filter holder. The borosilicate fiberglass filters were shown to produce excessive interference, making quartz quantification impossible. It was concluded that, while the DR/FT-IR method is potentially useful for on-filter measurement of quartz in dust samples, the use of PVC filters produced the most accurate results.
authors: a Office of Mine Safety and Health Research, National Institute for Occupational Safety and Health , Spokane , Washington.
authors: Arthur L
authors: AL
authors: Miller
authors: Nathaniel C
authors: NC
authors: Murphy
authors: Sean J
authors: SJ
authors: Bayman
authors: Zachary P
authors: ZP
authors: Briggs
authors: Andrew D
authors: AD
authors: Kilpatrick
authors: Courtney A
authors: CA
authors: Quinn
authors: Mackenzie R
authors: MR
authors: Wadas
authors: Emanuele G
authors: EG
authors: Cauda
authors: Peter R
authors: PR
authors: Griffiths
mesh_terms: D061808:Air Filters; D000395:Air Pollutants, Occupational / Q000032:analysis*; D003031:Coal / Q000032:analysis*; D003032:Coal Mining; D004391:Dust / Q000032:analysis*; D009314:National Institute for Occupational Safety and Health, U.S.; D016273:Occupational Exposure / Q000032:analysis; D011791:Quartz / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014481:United States
chemical_list: D000395:Air Pollutants, Occupational; D003031:Coal; D004391:Dust; D011791:Quartz
keywords: coal dust; diffuse reflection spectrometry; silica; α-quartz
references: Am J Ind Med. 2003 Aug;44(2):141-7
references: 12874846
references: Occup Environ Med. 2005 Oct;62(10):670-4
references: 16169911
references: J Environ Monit. 2008 Jan;10(1):96-101
references: 18175022
references: Appl Spectrosc. 2008 Apr;62(4):377-82
references: 18416894
references: J Environ Monit. 2008 May;10(5):671-8
references: 18449405
references: Am J Ind Med. 2008 Sep;51(9):633-9
references: 18626906
references: Ann Occup Hyg. 2009 Aug;53(6):639-49
references: 19531809
references: Ann Occup Hyg. 2010 Aug;54(6):697-709
references: 20660144
references: Appl Spectrosc. 2011 Mar;65(3):243-9
references: 21352643
references: Occup Environ Med. 2011 Dec;68(12):908-13
references: 21597107
references: J Environ Monit. 2012 Jan;14(1):48-55
references: 22130611
references: Anal Bioanal Chem. 2014 Jul;406(19):4715-24
references: 24830397
references: Aerosol Sci Technol. 2013;47(7):724-733
references: 26719603