Determination of Sulfuric Acid and Ammonium Sulfates by Means of a Computer-Controlled Thermodenuder System

Sulfuric acid and ammonium sulfates In air are sampled by means of two CuO coated denuders at temperatures of 120 and 240 °C, respectively. The tubes are heated to 800 °C and the liberated SO2 is measured by means of a flame photometric detector. The interference of Inorganic and organic sulfur species can be avoided by passing the sample stream through PbO2 and an active carbon-coated denuder. The detection limit Is 0.1 μg m-3 H2SO4 or ammonium sulfate at a sampling time of 5 mln and 0.02 μg m-3 at a sampling time of 60 min. The system Is completely automated and can function properly without any human assistance.