One thousand composited particulate samples collected by the National Air Surveillance Network in 1970 on glass fiber filters were analyzed for 24 trace elements by spark-excited direct reading emission spectrometry. After acid extraction, the lithium chloride stabilized extracts were analyzed in duplicate using a rotrode with indium as an internal standard. Interference corrections and calibration data were frequently updated during analyses by special minicomputer programs. Iron, calcium, aluminum, magnesium, zinc, and manganese were found in unused filters. Precision data on samples had a median relative standard deviation of 14% for all elements. The median spike recovery was 97%, excluding tin with 11 to 28%. Analysis of different portions of the same filters gave average concentration differences with a median of 14%. Detection limits for all elements and lead analysis by both atomic absorption and optical emission are reported. Zinc and tin data were unacceptable due to poor precision or accuracy.

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