Development of Passive Sampler Technology for Simultaneous Sulfur Dioxide and Nitrogen Dioxide Monitoring

摘要

A new type of passive sampler, which can easily determine sulfur dioxide (SO_2) and nitrogen dioxide (NO_2) simultaneously in ambient air, has developed. The passive sampling method for analysis of SO_2 has more difficult than NO_2 chiefly because of following two problems. The first one is that SO_2 has high absorptivity. Therefore, it is much absorbed in the materials used as the absorption and diffusion filter in sampler, and the second one is that the sulfate ion, to which absorbed SO_2 is oxidized, is usually contained in filter used as sampler parts. Thus, blank concentration of sulfur ion in sampler is higher. As a result of exposure experiments using a wind tunnel to evaluate the materials used as absorption and diffusion filter, the passive sampler which polyethylene membrane is used as an absorption layer, and polyethylene and polypropylene as the first and second diffusion layer was found to have the most suitable sampler for analyzing SO_2 and NO_2. The precision and detection limit of this method was found to be satisfactory. The method established in this study has been applied to the evaluation of air quality at the five major cities in China since September 1997.