Sample preparation methods for four-wipe composite dust wipe samples, used by nine different laboratories accredited under the U.S. Environmental Protection Agency (EPA) National Lead Laboratory Accreditation Program (NLLAP), were evaluated to select two methods most likely to provide the best overall performance among multiple laboratories, based on accuracy, precision and practicality of the methods. The best performing methods involved (1) hot nitric acid/hydrogen peroxide digestion and (2) nitric acid ultrasonication. In a second round of testing, two sets of composite dust wipe samples with known amounts of lead were submitted blind to each of the nine laboratories to be prepared for analysis using these two sample preparation methods. Results showed that both methods are capable of meeting all EPA NLLAP requirements for accuracy (recovery) and precision. The ultrason ication method had superior performance at lower cost.

ASTM Subcommittee E06.23 on Abatement/Mitigation of Lead Hazards has developed a number of standards that are concerned with the sampling of lead in environmental media, namely paint, dust, soil and airborne particulate. An ASTM practice for the collection of airborne particulate lead in the workplace has been published. New ASTM standards for the collection of dry paint film samples, surface soil samples, and surface dust wipe samples for subsequent lead analysis have also been promulgated. Other draft standards pertinent to lead sampling are under development. The ASTM standards concerned with lead sample collection are accompanied by separate sample preparation standard practices and a standard analysis method. Sample preparation and analytical methods have been evaluated by interlaboratory testing; such analyses may be used to assess the efficacy of sampling protocols.