REFRIGERATED MULTIBED ADSORPTION IN SAMPLING AND ANALYSIS OF ATMOSPHERIC LIGHT-HYDROCARBONS AT PPB (V V) AND SUB-PPB (V/V) CONCENTRATIONS/

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 deg rees C) vs. ambient temperature cartridges filled with a combination o f carbonaceous packings. The quantitative differences essentially conc ern some of the lower molecular weight compounds present in higher con centrations, e.g., ethane and propane, as well as toluene. These resul ts have been evidenced from a field comparison involving parallel samp lings with both refrigerated and ambient temperature systems and canis ter collection for reference. The site selected for study is a semi-ur ban area receiving low traffic pollution inputs. The concentrations pr ovided by these refrigerated tubes are close to those obtained with th e canister which is the sampling method giving the highest concentrati on values in a larger number of compounds. (C) 1997 Elsevier Science B .V.