Research Projects

A study was conducted to evaluate errors in the determination of atmospheric sulfate and nitrate employing filter sampling. Seven filter media were evaluated including Fluoropore, Whatman 41, Gelman GA-1, Gelman A, Gelman Spectrograde, Gelman EPA Grade and MSA 1106BH. The evaluation employed both field sampling and laboratory studies of the interaction of filter media, particulate matter and potential oxidation catalysts with pollutant gases (SO2, NO2, HNO3, NH3, O3).

Field studies demonstrated that fluoropore filter samples exhibited the lowest levels of artifact sulfate and nitrate, consistent with the behavior of clean Fluoropore filters in laboratory exposure studies. Glass and cellulose fiber high volume filter samples provided significant levels of both artifact sulfate and nitrate in field and laboratory studies. Particulate matter exhibited only a negligible role in influencing artifact sulfate. Manganese and copper oxide on filters was shown to produce sulfate from SO2 exposure. Soot, iron and vanadium oxides had no effect. Further work is necessary to establish the relevance of the results with metals to atmospheric conditions. Fluoropore filters are recommended for future atmospheric sulfate and nitrate monitoring.