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Photoacoustic FTIR spectroscopy for crystalline sillca analysis.

Zhuang-Z; Schwerha-D; Chen-B; Feather-G; Soderholm-S
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 1998 May; :75
The National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods includes three laboratory methods for measuring crystalline silica: X-ray diffraction (XRD), infrared spectroscopy (IR), and colorimetry (VIS). The purpose of this study was to determine if photoacoustic Fourier transfonn infrared (PA-FTIR) spectroscopy could be a viable alternative for laboratory analysis of crystalline silica samples. One benefit of PA-FTIR spectroscopy is that it is a nondestructive direct-on-filter method. In a preliminary study, crystalline silica dusts were generated using a fluidized-bed aerosol generator with a quartz stock standard (Min-U-Sil 5). The size distributions of the generated aerosols were determined using a mico-oriface uniform deposit impactor. The samples used in the PA-FTIR analysis were collected using 9-mm portions of 2S-mm vinyl metrlcel (VM-l) fillters loaded into 25-mm cassettes, which were attached to nylon cyclones, at a flow rate of 1.7 L/min. The respirable crystalline silica dust samples were weighed and then analyzed by PA-FTIR spectroscopy. Samples with different masses were collected. Multiple measurements of the samples were conducted to determine reproducibility of the analysis technique. The mass medium aerodynamic diameter of the samples on the filters was estimated to be 1.0 mm with a geometric standard deviation of 1.8 by correcting the size distribution from the impactor samples using the ACGIH definition of respirable particulate mass. A calibration curve was constructed. The limit of detection was determined to be less than 10 mg of quartz. Using 32 FTIR scans for each measurement, the relative standard deviation of replicate measurements of one filter was below 10%. These preliminary data indicate that PA-FTIR is worth additional study to determine whether it may be valid laboratory method for directon-filter measurement of crystalline silica.
Analytical-Method; Analytical-methods; Spectrographic-analysis; Spectrophotofluorometry; Spectroscopes; Sampling-methods; Aerosol-generators; Laboratory-techniques; Filters; Silica-dusts; Dust-analysis; Dust-samplers; Photofluoroscopy; Acoustics; Infrared-spectrophotometry; Infrared-spectroscopy; Laboratory-equipment; Analytical-instruments; Respirable-dust; Measurement-equipment
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American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia