Environmental Air Monitoring Using Thermal Desorption Tubes
Oral Presentation
Prepared by R. Helmich1, B. Bohn1, J. Beihoffer1, J. Hoban1, T. Talarski1, A. Eisele2
1 - US Environmental Protection Agency - National Enforcement and Investigations Center, Bldg. 25, Ent. E-3, Box 25227, Denver Federal Center, Denver, CO, 80225, United States
2 - Environmental Protection Agency - Region 8, 1595 Wynkoop Street, Denver, CO, 80202, United States
Contact Information: [email protected]; 303-462-9149
ABSTRACT
The Environmental Protection Agency’s (EPA) National Enforcement Investigations Center (NEIC) has undertaken an effort to implement advanced capabilities to monitor air emissions around industrial plant fence lines where volatile organic compound (VOC) sources are potentially present. Part of this air monitoring initiative has involved implementing the use of thermal desorption (TD) tubes to collect samples via passive diffusion. The EPA has deployed TD tubes to several locations around the country and collected preliminary data demonstrating their performance for benzene, toluene, ethylbenzene, xylenes, and several other analytes of interest. Initial studies have shown that gaseous calibration standards yield working curves with excellent linearity. Evacuated air sampling canisters with flow restrictors have been deployed along side TD tubes for comparison purposes. The results of the canister to TD tube comparisons have shown differences between canister and tube sampling that might be explained by sampling rate or relative bias due to variable analyte concentration in the environment and canister sampling time. Comparison studies between Carbopack X* and Tenax TD* tubes showed minor differences in measured analyte concentrations, but more work is needed to determine if the observed differences are statistically significant. Lastly, statistical analysis of duplicate TD samples is used to explain a seemingly systematic pattern of one TD tube with higher analyte concentrations.
*Note: Reference herein to any specific commercial product, process, or service by trademark, manufacturer, or otherwise, does not imply its endorsement, recommendation, or favoring by the US Government.
Oral Presentation
Prepared by R. Helmich1, B. Bohn1, J. Beihoffer1, J. Hoban1, T. Talarski1, A. Eisele2
1 - US Environmental Protection Agency - National Enforcement and Investigations Center, Bldg. 25, Ent. E-3, Box 25227, Denver Federal Center, Denver, CO, 80225, United States
2 - Environmental Protection Agency - Region 8, 1595 Wynkoop Street, Denver, CO, 80202, United States
Contact Information: [email protected]; 303-462-9149
ABSTRACT
The Environmental Protection Agency’s (EPA) National Enforcement Investigations Center (NEIC) has undertaken an effort to implement advanced capabilities to monitor air emissions around industrial plant fence lines where volatile organic compound (VOC) sources are potentially present. Part of this air monitoring initiative has involved implementing the use of thermal desorption (TD) tubes to collect samples via passive diffusion. The EPA has deployed TD tubes to several locations around the country and collected preliminary data demonstrating their performance for benzene, toluene, ethylbenzene, xylenes, and several other analytes of interest. Initial studies have shown that gaseous calibration standards yield working curves with excellent linearity. Evacuated air sampling canisters with flow restrictors have been deployed along side TD tubes for comparison purposes. The results of the canister to TD tube comparisons have shown differences between canister and tube sampling that might be explained by sampling rate or relative bias due to variable analyte concentration in the environment and canister sampling time. Comparison studies between Carbopack X* and Tenax TD* tubes showed minor differences in measured analyte concentrations, but more work is needed to determine if the observed differences are statistically significant. Lastly, statistical analysis of duplicate TD samples is used to explain a seemingly systematic pattern of one TD tube with higher analyte concentrations.
*Note: Reference herein to any specific commercial product, process, or service by trademark, manufacturer, or otherwise, does not imply its endorsement, recommendation, or favoring by the US Government.
