Annular Denuders and Filter Packs Designed to Measure Ambient Levels of Acidic and Basic Air Pollutants

The GC-MS data files for three field samples were also analyzed [3]. The identities of the target compounds were determined by using both GC retention times and a combination of forward and reverse spectral matching techniques with stringent matching parameters. The identification of other compounds not on the target list was based on a Finnigan search technique. The application of the pattern recognition scheme to the transformed data for the target compounds resulted in 88% correct classification. The compound identification results were 85% accurate. There were 75 different nontarget compounds identified in 120 occurrences in the three samples. The classification results agreed very well for the two class I and class 2 spectra. However, a very large number of alkanes and alkenes were incorrectly classified as chlorocompounds. Further details of this study are given in references [2], [3], and [4]. Although the research described in this article has been funded by the U.S. Environmental Protection Agency under Cooperative Agreement CR-811617 with the University of Illinois at Chicago, it has not been subjected to Agency review. The mention of commercial products does not constitute endorsement or recommendation for use.