Laboratory and field investigations of a new and simple design for the parallel plate denuder

Diffusion denuders are commonly used for collection of water soluble atmosp heric gases. Denuder plates made of glass with silica coating were however difficult to handle in field measurements, and also had wettability problem s. In this paper, we describe a new design of parallel plate denuder consis ting of perfluoralkoxy (PFA) plates and polyester sheets. The parallel plat e denuder was coupled on-line to ion chromatography for analysis of atmosph eric HNO3 and SO2. With time resolution of 20 min, the detection limits for both gases were 6 ppt(v). Memory effect was found to be significant for HN O3 especially at high humidity with the long sample inlet tube. Particle lo sses due to diffusion and electrostatic effects in the denuder were investi gated and compared with theory. Particle loss in the sample inlet tube was found to play an important role by reducing the number of charged particles entering the denuder. The instrument was applied in two European Union fie ld measurement campaigns, and the intercomparison results are presented in this paper. (C) 2001 Elsevier Science Ltd. All rights reserved.