Evaluation of direct-on-filter methods for the determination of respirable alpha-quartz.
Lorberau CD; Carsey TP; Fischbach TJ; Mulligan KJ
Appl Occup Environ Hyg 1990 Jan; 5(1):27-35
A comparison was made of two direct on filter methods for respirable alpha-quartz (14808607) determination for which the filter may be analyzed by x-ray diffraction (XRD) without processing. The filters had to have good retention of the sample dust to be easily handled without loss, therefore the authors used silver membrane and mixed cellulose ester (MCE) filters. The direct on filter method produced results which were similar to those obtained by the reference method, NIOSH Method-7500, over the range from 200 micrograms to 1.2 milligrams. The authors state that with 95 percent confidence any single measurement by the direct on MCE method would produce a result within 25 percent of any single measurement by Method-7500 under the same experimental condition. With the direct on silver method the results fell within 30 percent. The direct on filter methods were more attractive due to substantial savings in time and effort. There was a suggestion of a bias between the direct on silver Method and Method-7500 which may be ascribed to a mismatch between the particle size distribution of the calibration material and the mine dust which was used as a test aerosol. Using two different procedures, calibration curves were obtained; one was prepared by depositing alpha-quartz aerosol directly on the filter and the other by filtration of an isopropanol suspension of the same reference material on the filters. A marked difference in the two curves was noted indicating that samples must be referred to calibration curves prepared in an analogous manner. A small aerosol generation system was presented for the preparation of direct on filter calibration samples.
AIHYEX; NIOSH-Author; Silicosis; Respiratory-system-disorders; Respirable-dust; Filtration; Filter-materials; Analytical-methods; Chemical-analysis; Airborne-dusts; Lung-irritants
Applied Occupational and Environmental Hygiene