Evaluation of an annular denuder tubes for atmospheric PAH partitioning studies—1: evaluation of the trapping efficiency of gaseous PAHS

This paper is an evaluation of the gas phase collection efficiency of a commercially available annular denuder sampler used to collect gas and particle phase semivolatile organic compounds. Laboratory and field experiments were carried out to determine the gas phase collection efficiency using naphthalene as reference compound. Laboratory tests were performed to study the influence of environmental conditions (temperature, relative humidity and gas phase concentration) and sampling conditions (sampling flow rate, and sampling duration) on the collection efficiency. During laboratory experiments, the collection efficiency of the gas phase was measured using a dynamic gas generator. It was above 90% for a range of experimental conditions covering: temperature from 9°C to 39°C, relative humidity from 30% to 90%, sampling duration up to 14 h, flow rate of 1 and 2 m3 h−1 and quantity of gaseous naphthalene considerably higher than the one usually collected during atmospheric sampling. Additionally, field experiments were carried out to test the matrix effect on the denuder performances. During these field experiments, and because the gaseous and particle atmospheric phases were trapped and analysed separately, it was possible to calculate the collection efficiency of the most volatile polycyclic aromatic hydrocarbons (PAHs). It was 100% assuming a relative standard deviation of 10% on this calculation. This set of results shows that the denuder-based sampling method is suitable for the sampling of the most volatile PAHs.