In an earlier research poject supported by the National Science Foundation, a triple-path denuder (TPD) assembly for ambient sampling of sulfate and/or nitrate compounds was constructed. This device contains a series of denuders and filter packs which is intended to permit sampling and protection of sulfate nitrate particles obtained from polluted urban atmospheres for species analysis by x-ray diffraction techniques. In the current project, further laboratory tests are planned: 1) the ability for this TPD instrument to collect artificially prepared aerosols of nitrates and sulfates; 2) to determine the lower limit of detection of these materials; and 30 to assess the extent to which the denuder systems of the TPD protect the samples from artifact reactions. Additional sampling at Denver, Colorado, is planned to test the system in actual field conditions where significant urban chemical products of this nature are known to occur. The proposal also includes quantitative analysis of the collected particulate matter by x- ray reference intensity and x-ray fluorescence procedures.
