Performance of laboratories measuring silica in the Proficiency Analytical Testing program.
Shulman-SA; Groff-JH; Abell-MT
Am Ind Hyg Assoc J 1992 Jan; 53(1):49-56
A study was conducted to identify trends in the reported silica (14808607) results for the first 101 rounds of the Proficiency Analytical Testing (PAT) program, particularly trends in the bias and variability of the results reported during the last 70 rounds. The silica samples sent to PAT program laboratories each round consist of five polyvinyl-chloride filters. One of the filter samples was a blank and four filters contained varying amounts of silica dust and one or more of the following contaminant dusts: magnesium-silicate, coal dust, or calcite. Analysis of the data indicates that the colorimetry (COL) method has tended to give somewhat lower results than the two other methods, x-ray diffractometry, and infrared spectrometry. This difference becomes larger at higher loadings where the COL method gives results more than 20 micrograms lower. Some possible biases appear to be associated with different particle sizes and matrices. In general, silica analyses have improved over time, and this has taken place in all three methods. Examination of the most recent round indicates that it is no longer necessary to transform the silica data for purposes of routine PAT analyses.
NIOSH-Author; Analytical-methods; Analytical-chemistry; Chemical-analysis; Laboratory-testing; Quality-control; Silica-dusts; Mineral-dusts
American Industrial Hygiene Association Journal