Effect of Conventional Water Pretreatment Devices on Polar Compound Analysis

In general, water vapor in the sample gas can cause adverse effect on analytical instruments. Therefore, the removal of water vapor from the sample gas is a pivotal issue when analyzing polar compounds. The effects of water pretreatment devices on polar compound analysis were investigated in this study. Nafion dryer and Cooler, which are the most widely used water pretreatment device in the world, were compared. Three types of Nafion dryers and two types of Coolers were used. The main target polar compounds were methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), isobutyl alcohol (i-BuAl) and butyl acetate (BuAc) which are designated as odorous compounds in Korea. In order to investigate the effect of the water pretreatment device on target compounds, the water vapor removal test and the recovery test were conducted. When the water vapor removal test was performed with 50% and 90% of RH, Nafion dryers (65.4%-96.6%) showed higher water removal efficiencies than those of Coolers (34.2%-67.2%). During a recovery test, Nafion dryers revealed lower recovery rate and lower reproducibility than Coolers. In particular, Nafion dryers showed very low recovery rate and low reproducibility with respect to MEK and i-BuAl which had high water solubility. It was found that Nafion dryers were not suitable for polar compounds of concern. In addition, Coolers had limitation in water vapor removal as well. Therefore, further research on water pretreatment devices that can overcome the problems is necessary.