Collaborative Tests Of Two Methods For Determining Free Silica In Airborne Dust.
NIOSH 1983 Feb:156 pages
Investigation was conducted to determine free silica (14808607) in airborne dust by X-ray diffraction and infrared methods. Fifteen laboratories participated in sampling and analyses. The diffraction method consisted of using airborne dust and trapping silica on a polyvinylchloride filter of a personal sampling pump. The sample was ashed in a muffle furnace. Silica and other residue were suspended in solvent and uniformly deposited on a silver membrane filter. Silica was analyzed by diffraction and the peak intensity was compared with calibration standards. For the infrared method, coal mine dust was sampled similarly. The residue from ashing was suspended in a solvent and redeposited on a transparent filter. Analysis was done by measuring absorption at 800 per centimeters. The percent relative standard deviation for samples containing 50 to 200 micrograms of silica ranged from 15 to 23 percent by the diffraction method. The personal sampling method added significantly to interlaboratory variability with an estimated error range of 17 percent. For the infrared method, the standard deviation was 13 to 25 percent over the range of 25 to 60 micrograms of silica in coal mine dust. Sampling pump error by this method was about 24 percent. The author concludes that the magnitudes of error are large for these two methods and that the errors must be reduced for the methods to be useful.
NIOSH-Contract; Safety-research; Pollution; Air-quality-control; Air-samplers; Air-sampling-equipment; Airborne-fibers; Sampling-equipment; Respiratory-infections; Contract-210-79-0059;
NTIS Accession No.
NIOSH, Public Health Service, U.S. Department of Health and Human Services, Cincinnati, Ohio, NTIS PB83-232-322