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Evaluation of a portable x-ray fluoescence instrument for the determination of lead in workplace air samples.

Morley-JE; Ashley-K; Deddens-J; Clark-S
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 1998 May; :58
OSHA regulations for worker exposure to lead specify worker protection levels based on airborne concentrations of lead dust. The rapid, on-site determination of lead in air filter samples using a portable X-ray iluoresence (XRF) instrument with an attachment to hold the filter would expedite the exposure assessment process and facilitate compliance with the OSHA standard. A total of 65 lead in air filter samples were collected with closed-faced, 37-mm cassettes at bridge blasting lead-abatement projects. The lead loading range of the sample set was 0.1 to 1514.6 mg of lead/sample. Samples were initially analyzed with a field portable Niton7 700 Series XRF using an experimental nondestructive XRF method. Samples were subsequently analyzed using the NIOSH Sampling and Analytical Method 7105 (Graphite Furnace AA) as a reference method. The paired data were not normally distributed; therefore, the nonparametric Wilcoxon signed rank test was used. There was no statistically significant difference between the data from the field portable XRF method and the NlOSH method (p-value= 0.72). Linear regression of the data resulted in a slope of 0.959 and an r2 of 0.985. The XRF instrument limit of detection (LOD) and limit of quantitation (LOQ) were determined to be 6.2 and 17.1 mg of lead/sample, respectively. The XRF method accuracy was + / - 27%. These data indicate that there is no statistically significant difference between the field portable XRF method and NIOSH Method 7105. The instrument LOQ of 17.1 mg of lead/sample is sufficiently sensitive to quantitate lead exposures below the OSHA action level of 30 mg/m3, given a sample volume of 570 liters. Although the method accuracy of + / - 27% is greater than the NIOSH accuracy criterion of + / - 25%, the method was evaluated using field samples. Laboratory prepared aerosol samples would be expected to give better precision. This research led to the development of NIOSH draft Method 7702, "Lead by Field Portable XRF."
Analytical-Method; Analytical-methods; Lead-compounds; Lead-dust; Sampling; Sampling-methods; Exposure-assessment; Analytical-instruments; X-ray-fluorescence-analysis; Regulations; Standards; Air-sampling; Air-sampling-equipment; Filters
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American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division