Determination of water soluble trace gases in ambient air by condenser- type diffusion denuder coupled ion chromatography

An automated method is developed for simultaneous determination of water soluble gases at parts per trillion level in the environmental air. The method involves temperature-humidity control of sample air using a thermostated humidifier, collection of analyte gases by condenser-type effluent diffusion denuder and subsequent effluent analysis by ion chromatography. The detection limits (3σ) of the method for CH₃COOH, HNO₂ and SO₂ gases are 0.022, 0.019 and 0.009 ppbv, respectively. The precisions range from 0.3 to 3.0% RSD. The method has been successfully applied to urban air analysis and some results for nitrous acid and SO(x) in Seoul air are presented.