Development and evaluation of a novel gas and particle sampler for semivolatile chlorinated organic compounds in ambient air

A prototype annular diffusion denuder inlet has been adapted to a dichotomous sampler for the collection of organic compounds which occur in both the gas and particulate phase. The inlet selectively removes and efficiently preconcentrates atmospheric vapor-phase components by molecular diffusion prior to the collection of the particulate phase by filtration. Backup adsorbent cartridges collect any vapor-phase constituents which might volatilize from the collected particulate matter and submicron particles which might penetrate the filter media. Special techniques were developed for coating the annular denuder with solid adsorbents. Laboratory tests with lindane and hexachlorobenzene have demonstrated better than 98% trapping efficiency over a 24-h sampling period at contaminant concentrations representative of ambient air and under most simulated atmospheric conditions.