Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components

摘要

Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD.