Special Articles on Global and Regional Environment and Chemistry. A Simple Measurement Method of Nitrogen Dioxide in the Atmosphere with the Molecular Diffusion Sampler Using the Porous Polytetrafrafluoroethylene(PTFE) Tube.

A simple measurement method with the molecular diffusion sampler using porous PTFE tube to measure nitrogen dioxide (NO2) concentration in the atmosphere was examined. The porous PTFE tube (length: 8 cm, outside diameter: 8 mm, inside diameter: 6 mm, pore size: 1.0 pm, porosity 85%) used in this study was small but had large diffusion area. The method was as follows: a molecular diffusion sampler which was enclosed a collection liquid (30% triethanolamine-GO% dimethyl sulfoxide-10% ethylene glycol) in the porous PTFE tube was exposed in the exposed chamber and the atmosphere. And then, NO2- in an aqueous extract of the collection liquid of the sampler was analyzed with an ion chromatograph. According to the chamber experiment, the influence of meteorological factors (temperature, relative humidity and wind velocity) on this sampler was examined. As to the temperature, the amount of collection of NO2-, with sampler was caused 18% increase owing to 10°C rise of temperature for measurement of 2-. On the other hand, the influence of relative humidity was not noticed. And the increase of wind velocity 1 m/s was caused only 3% increase of amount of collection. But in the actual applications the influence of wind velocity was almost neglected. It bec ame evidence that the sampler employed in this study was small and light and the extraction procedure was easy since the collection liquid was used and moreover the deteimina tion was rapid by the use of ion chromatograph. And yet, this method was recognized to be a high sensitive measurement (minimum amount of exposure: 12 ppb⋅h) that was enou measure NO2 concentration in general atmosphere and room atmosphere even in a pe riogdh otof only an hour level in spite of molecular diffusion sampler. Hence, it was thought that this sampler was most adap t to use as a short term sampl er f or one day level and personal sampler of NO2 measurement in the case of considerati on of the NO2 concentration in the atmosphere.