Volume 8, Issue 3 (March 2011)
Development of Two Sample Preparation Methods for Determination of Lead in Composite Dust Wipe Samples
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 ultrasonication method had superior performance at lower cost.