Proficiency Analytical Testing (PAT) silica variability, 1990-1998.
Eller PM; Feng HM; Song RS; Key-Schwartz RJ; Esche CA; Groff JH
Am Ind Hyg Assoc J 1999 Jul/Aug; 60(4):533-539
Industrial hygiene laboratories use one of three analytical techniques (X-ray diffraction spectrometry, infrared absorption spectrometry, and colorimetric spectrophotometry) for the quantitative determination of crystalline silica. Interlaboratory variability historically has been high for these analyses (about 25-35% relative standard deviation). Agreement between laboratories, as measured by the American Industrial Hygiene Association Proficiency Analytical Testing program over the period April 1990 through April 1998, was studied. Analysis of over 11,000 data points (laboratory/sample/round combinations) showed some significant differences between analytical methods in their relative recovery and precision, although overall mean recoveries were similar for the three techniques. Relative recovery of colorimetric results (but not those of the X-ray or infrared results) was significantly affected by sample loading in the range 40-170 microg silica per sample. Differences on the order of 5-10% were produced in some intermatrix comparisons for infrared and colorimetric recoveries, but not for those of X-ray. X-ray and infrared techniques were both more precise than colorimetric. Small differences, on the order of 2-5%, were observed in the interlaboratory and intralaboratory relative standard deviations between different matrices for X-ray and infrared analyses, but not for the more variable colorimetric results.
Laboratories; Laboratory-techniques; Metals; Solvents; Fiber-deposition; Filters; Statistical-analysis; Infrared-spectrophotometry; Infrared-spectroscopy; Analytical-methods; Analytical-chemistry; Analytical-processes; Silica-dusts; Silicates; Quartz-dust; X-ray-diagnosis; X-ray-analysis
National Institute for Occupational Safety and Health, Division of Physical Sciences and Engineering, 4676 Columbia Parkway, Cincinnati, OH 45226-1998
American Industrial Hygiene Association Journal