Abstract
A glass impactor was designed and evaluated along with an annular denude/filter pack system. The glass impactor has a 50% aerodynamic cutoff of 2.1 ..mu..m at a flow of 10 L min/sup /minus/1/ and allows a quantitative transfer of gases and fine particles to the annular denuder and filter pack components. Fine particle and gas concentrations, determined by using the glass impactor along with the annular denuder/filter pack, were in good agreement with those obtained with colocated reference samplers. Measurements of SO/sub 2/, HNO/sub 3/, and HNO/sub 2/ gases showed mean collection efficiencies of 0.993, 0.984, and 0.952, respectively, which compare well with predicted values. Additionally, it was found that artifact formation of nitrate and nitrite ions, representing about 5-10% of the concentrations of HNO/sub 3/ and HNO/sub 2/, occurs in the Na/sub 2/CO/sub 3/-coated annular denuder. Corrections for these artifacts were made with a second Na/sub 2/CO/sub 3/-coated annular denuder. The results of this pilot study suggest that the glass impactor/annular denuder/filter pack sampling system is suitable for measuring acidic aerosols and gases.
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