LABORATORY AND ANALYTICAL METHOD PERFORMANCE OF LEAD MEASUREMENTS IN PAINT CHIPS, SOILS, AND DUSTS

The National Lead Laboratory Accreditation Program (NLLAP) recognizes laboratories capable of analyzing lead in paints, soils, a nd dusts. N LLAP requires successful participation in the Environ mental Lead Prof iciency Analytical Testing (ELPAT) program. For paint chip analyses, l aboratory-to-laboratory Health Service, Centers variability is about 1 0% relative standard deviation (RSD) for lead levels near 0.5%, the HU D definition for Disease Control and of lead-based paint. For soil ana lyses, RSDs are about 9 to 10% near relevant federal soil standards an d 16% near the lowest state bare soil standard that currently exists. For dust wipe analyses, RSDs range from 10 to 16% for lead levels near relevant HUD standards. Of participating laboratories, 92 to 93% cons istently meet ELPAT performance limits. A variety of analytical method s gives similar results. No conclusive significant differences were fo und among most frequently used hotplate and microwave sample preparati on techniques. In addition, several participating laboratories have su ccessfully used ultrasonic extraction methods, a method suitable far u se at abatement sites. The three most frequently used instrumental tec hniques, flame atomic absorption (FAA), inductively coupled plasma-ato mic emission spectroscopy (ICP-AES), and graphite furnace atomic absor ption show no statistically significant differences in ability to meet ELPAT performance limits. However, small statistically significant bi ases between these methods sometimes occur. The magnitude of biases is less than 5% of the corresponding laboratory mean near relevant feder al standards except for lead levels near the lowest HUD lead wipe stan dard, where biases can be as high as 8%. Other instrumental methods th at have been used successfully include ICP-mass spectroscopy,direct cu rrent plasma-atomic emission spectroscopy, dithizone spectrophotometry , and anodic stripping voltametry.