Refrigerated multibed adsorption in sampling and analysis of atmospheric light hydrocarbons at ppb (v/v) and sub-ppb (v/v) concentrations

Abstract : Higher ppb (v/v) and sub-ppb (v/v) concentrations of airborne C-2-C-8 light hydrocarbons are obtained when analyzed by refrigerated (-10 degrees C) vs. ambient temperature cartridges filled with a combination of carbonaceous packings. The quantitative differences essentially concern some of the lower molecular weight compounds present in higher concentrations, e.g., ethane and propane, as well as toluene. These results have been evidenced from a field comparison involving parallel samplings with both refrigerated and ambient temperature systems and canister collection for reference. The site selected for study is a semi-urban area receiving low traffic pollution inputs. The concentrations provided by these refrigerated tubes are close to those obtained with the canister which is the sampling method giving the highest concentration values in a larger number of compounds