The efficiency of alkaline extraction for the recovery of hexavalent chromium (CrVI) from paint samples and the effect of sample storage on CrVI recovery
Rania A. Sabty-Daily,Kate K. Luk,John R. Froines
Analyst Pub Date : 05/13/2002 00:00:00 , DOI:10.1039/B106701J
Abstract

Workplace exposures to CrVI, a human carcinogen, are significant in spraying operations of chromate-containing paints. Accurate determination of CrVI in paint aerosol air samples is important in assessing a worker’s exposure to CrVI. National Institute for Occupational Safety and Health method 7604 is widely used for determining CrVI in air samples. It utilizes an alkaline extraction procedure. It was historically validated for paint aerosol samples containing 24.5 to 61.5 μg of CrVI. The literature documented potential airborne CrVI exposures greater than 61.5 μg in recent paint spraying operations. The efficiency of the alkaline method at extracting CrVI from paint samples containing 250 to 3000 μg of CrVI was determined. Paint was prepared, sampled, extracted twice and then digested. Extracts were analyzed for CrVI and digestates of the residual Cr were analyzed for total Cr. Alkaline extraction of paint samples using NIOSH method 7604 resulted in quantitative recoveries for paint samples with CrVI filter loadings from 250 to 3000 μg. A decrease in CrVI extraction efficiency was observed in samples containing >1000 μg of CrVI. A second extraction improved the recovery of CrVI in these samples. Refrigerating paint aerosol samples for up to 2 weeks did not affect their CrVI content.