Controlled desorption trap (CDT): A water management technique for quantitative analysis of polar VOCs in ambient air
- Graseby/Nutech, Durham, NC (United States)
Compendium Method TO-14 details the analysis of volatile organic compounds (VOCs) in ambient air using cryogenic preconcentration for sample enrichment. When working with high humidity sample volumes of 50 ml and greater, water management becomes critical. Compendium Method TO-14 specifies the Nafion{reg_sign} semi-permeable membrane to reduce water vapor in the sample stream during cryogenic concentration. The same mechanism responsible for this effective dehydration of the sample compromises recoveries of polar species. Consequently, alternate water management techniques are necessary when polar compounds are analyzed. The CDT is effective as a water management techniques since it allows volatile organics, collected on a primary cryotrap, to vaporize at a temperature that limits the partial pressure of water vapor. Temperature control of the cryotrap and the total volume of the desorption gas are essential parameters in optimizing CDT. A secondary cryotrapping step is necessary to refocus the slowly desorbed sample prior to injection to a GC or GC/MS.
- OSTI ID:
- 197490
- Report Number(s):
- CONF-9405167--
- Country of Publication:
- United States
- Language:
- English
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