A DIFFUSIVE SAMPLER OF GASEOUS POLLUTANTS BY COLLECTION IN LIQUID MEDIA

A diffusive sampler to be used with an absorbing solution for the collection of workplace pollutants is described. It is constructed of polytetrafluoroethylene and the diffusion is controlled by a number of small channels. The sampler has been evaluated in the laboratory using ammonia and sulphur dioxide as test gases. The sampling rate was constant for different air concentrations and it agreed well with theoretical calculations. No effects from humidity were seen during sampling and no sample loss was observed after storage for up to 4 weeks. When the air velocity above the sampler was 0.1 m s–1 the sampling rate was 8%; lower than at velocities between 0.2 and 0.8 ms–1