HIGH UPTAKE RATE RADIAL DIFFUSIVE SAMPLER SUITABLE FOR BOTH SOLVENT AND THERMAL-DESORPTION

A new diffusive sampler with radically changed diffusive path geometry was developed. The small cylinder has a height greater than its radiu s; the diffusive surface is the external cylindrical one, and the adso rber is a coaxial inner cylindrical cartridge. Due to the high value o f diffusive area-path length ratio and to the high loading capacity of the adsorber (up to 80 mg for ethyl acetate), this original geometry allows high and constant sampling rates in a wide range of concentrati ons and exposure times. The cylindrical shape of the cartridge enables both thermal and solvent desorbing as well as active sampling. Using activated charcoal, exposure time can range from 30 minutes to 24 hour s, thus allowing monitoring both in the workplace and in the outdoor e nvironment. As an example, the 80 cm(3)/min uptake rate of benzene ass ures a detection limit as low as 2 mu g/m(3) after 24-hour exposure ti me. The uptake rate for 32 organics was measured experimentally, and r esults were found to be highly reproducible and unaffected by wind spe ed and airborne mixture composition.