Palmes E D, Johnson E R
Am Ind Hyg Assoc J. 1987 Jan;48(1):73-6. doi: 10.1080/15298668791384391.
When nitrogen dioxide (NO2) samplers were exposed at several reduced pressures, it was found that the sampling rate was correspondingly decreased; that finding did not agree with accepted diffusional theory. When the experiments were repeated using water vapor as the gas and molecular sieve as the sorbent, the observed sampling rates were in very good agreement with diffusional theory. These findings demonstrated that the pressure effect was not common to all diffusional samplers and suggested that there might be an alternate explanation for the results with NO2-triethanolamine (TEA). The best possibility appeared to be the dehydration of TEA that takes place at reduced pressures. That this is a very significant factor was demonstrated by simultaneous exposure to identical concentrations of NO2 at 1 atm and 50% or 0% relative humidity. In dry air the sampling rate was equivalent to that found previously at about 1/10 atm. The earlier results can be satisfactorily explained as indirect rather than direct effects of reduced pressure.
当二氧化氮（NO₂）采样器在几种减压条件下暴露时，发现采样率相应降低；这一发现与公认的扩散理论不一致。当使用水蒸气作为气体、分子筛作为吸附剂重复这些实验时，观察到的采样率与扩散理论非常吻合。这些发现表明，压力效应并非所有扩散采样器都具有，这表明对于二氧化氮 - 三乙醇胺（TEA）的结果可能存在另一种解释。最有可能的情况似乎是TEA在减压条件下发生脱水。通过在1个大气压以及50%或0%相对湿度下同时暴露于相同浓度的NO₂证明了这是一个非常重要的因素。在干燥空气中，采样率与之前在约1/10个大气压下发现的采样率相当。早期的结果可以令人满意地解释为减压的间接而非直接影响。
