National Institute for Occupational Safety and Health

“ Lead determination by ultrasonic extraction/ASV method is applicable to the on-site, field-based determination of lead in air filter samples, and also may be used for laboratory-based air filter sample preparation and analysis. INTERFERENCES: Thallium is a known interference, but its presence is unlikely in the vast majority of samples. Extremely high concentrations of copper may cause a positive bias. ”

“ For the latter, lead loadings cover the range from below the detection limit of 0.09 :g Pb per filter to loadings in excess of 1500 :g Pb per filter [4 ] . The method also has been evaluated with performance evaluation materials and by interlaboratory testing [35] . Lead recoveries from Certified Reference Materials (CRM s) were found to be quantitative ($90%) and equivalent to recoveries obtained using confirmatory analytical methods (NIOSH 7082, 7105, and 7300 [11] ) .
REFERENCES: [1] Wang J [1985] . Stripping analysis. New York: VCH Publishers. [2] Wang J [1996] . ”

“ SAMPLE PREPARATION: 3. Open the cassette filter holders and, with forceps, transfer the samples and b lank s to separate 50-m L centrifuge tubes. Push the filters to the bottom of the tubes with plastic rods. 4. Add 10 mL of 10% HNO 3 and cap the centrifuge tubes. 5. Place centrifuge tubes in ultrasonic bath, and agitate at room tem perature for at least 30 min. NOT E 1: The water level in the bath should be above the level of liquid within the centrifuge tubes. ”