CHRYSOTILE ASBESTOS (BULK): METHOD 9000, Issue 2, dated 15 August 1994 - Page 5 of 6 CALCULATIONS: 13.
Calculate the percentage of chrysotile in the bulk dust sample:
where: Îx = normalized intensity for sample peak b = intercept of calibration graph ( vs. W) m = slope of calibration graph (counts/µg) f(T) =
= absorption correction factor (Table 1)
R = sin ( T = Î Ag/(average ) = transmittance of sample ÎAg = normalized silver peak intensity from sample average
= normalized silver peak intensity from media blanks (average of six
values) W = mass of deposited sample in µg. NOTE: For a more detailed discussion of the absorption correction procedure, see references [5] to [8].
EVALUATION OF METHOD: This method is based on the work of B.A. Lange in developing P&CAM 309 [1,2]. Samples in the range of 1 to 100% chrysotile in talc were studied to establish the feasibility of an XRD method for airborne asbestos. Analytical precision was as follows: % Chrysotile in Talc
Sr (%)
100 10 7 5 3 1
6.9 4.7 9.8 8.2 10.1 12.5
This work also showed that bias of results after absorption corrections are made is negligible.
REFERENCES: [1] [2] [3] [4] [5]
Lange, B. A. Determination of Microgram Quantities of Asbestos by X-Ray Diffraction: Chrysotile in Thin Dust Layers of Matrix Material, Anal. Chem., 51:520(1979). NIOSH Manual of Analytical Methods, 2nd ed., V. 5, P&CAM 309, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 79-141 (1979). Perkins, R.L. and B.W. Harvey. U.S. Environmental Protection Agency Test Method for the Determination of Asbestos in Bulk Building Materials, EPA/600/R-93/116 (June, 1993). Criteria for a Recommended Standard...Occupational Exposure to Asbestos (Revised), U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-169 (1976). Leroux, J. and C. Powers. Direct X-Ray Diffraction Quantitative Analysis of Quartz in Industrial Dust Films Deposited on Silver Membrane Filters, Occup. Health Rev., 21:26 (1970). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
