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United States Department of Agriculture

Agricultural Research Service

Research Project: REDUCTION OF NUTRIENT LOSSES AND AERIAL EMISSIONS FROM LIVESTOCK PRODUCTION FACILITIES Title: Bias of Tedlar Bags in the Measurement of Agricultural Odorants

Authors
item Trabue, Steven
item Anhalt, Jen - FORMER USDA/ARS/SOMMRU
item Zahn, J - DOW AGROSCIENCES

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 24, 2006
Publication Date: August 9, 2006
Citation: Trabue, S.L., Anhalt, J., Zahn, J.A. 2006. Bias of tedlar bags in the measurement of agricultural odorants. Journal of Environmental Quality. 35:1668-1667.

Interpretive Summary: Odor regulations typically specify the use of dynamic dilution olfactometry (DDO) as a method to quantify odor emissions and Tedlar bags are the preferred holding container for grab samples. However, few studies have been conducted on how the integrity of the grab sample is maintained in Tedlar bags. This study was conducted to determine if Tedlar bags affect the integrity of sampled air from animal operations. Air samples were collected simultaneously in both Tedlar bags and Tenax thermal desorption tubes. Samples were collected from odorless air, air in contact with a synthetic odor solution; or air from a swine production facility. Chemical compounds in the air were analyzed by thermal desorption GC-MS-O (gas chromatography-mass spectrometer-olfactometry). Several background contaminants were identified from Tedlar bags (odorless air), which included the odorous compounds N,N-dimethyl acetamide (DMAC), acetic acid, and phenol. Samples taken from synthetic odor solution were affected by the residence time in the Tedlar bag with longer residence time leading to lower recovery of malodor compounds. After 24 hours of storage, recovery of volatile fatty acids (VFA) averaged 64%, 4-methylphenol and 4-ethylphenol averaged 10% and indole, and 3-methylindole were not detected at all. However, samples taken from swine production facility had better recovery than was predicted from laboratory studies. After 24 hours of storage, recovery of VFA averaged 76%, 4-methylphenol and 4-ethylphenol averaged 26% with both indole and 3-methylindole still not recoverable from Tedlar bags. Chemical compounds concentrations stored in Tedlar bags that were above their odor threshold were 33-65% lower after 24 hours of storage in Tedlar bags. These results indicate that significant odorant bias may occur when using Tedlar bags for the sampling of odors from animal production facilities. Research results described in this report provides academic scientist, regulatory scientists, and agricultural consultants valuable information on the effects of storing odorous air in Tedlar bags collected from animal production facilities.

Technical Abstract: Odor regulations typically specify the use of dynamic dilution olfactometery (DDO) as a method to quantify odor emissions, and Tedlar bags are the preferred holding container for grab samples. This study was conducted to determine if Tedlar bags affect the integrity of sampled air from animal operations. Air samples were collected simultaneously in both Tedlar bags and Tenax thermal desorption tubes. Sample sources originated from either a zero grade air tank, dynamic headspace chamber (DHC), or swine production facility and were analyzed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Several background contaminants were identified from Tedlar bags, which included the odorous compounds N,N-dimethyl acetamide (DMAC), acetic acid, and phenol. Samples from the DHC demonstrated that recovery of malodor compounds was dependent on residence time in the Tedlar bag with longer residence time leading to lower recovery. After 24 hours of storage, recovery of C3-C6 volatile fatty acids (VFA) averaged 64%, 4-methylphenol and 4-ethylphenol averaged 10% and indole, and 3-methylindole were below the detection limits of GC-MS-O. Surprisingly, field samples had better recovery than was predicted in laboratory studies. After 24 hours of storage, recovery of C3-C6 volatile fatty acids (VFA) averaged 76%, 4-methylphenol and 4-ethylphenol averaged 26%. However, indole and 3-methylindole were still not recovered from Tedlar bags. The odor activity value (OAV) of grab samples collected in Tedlar bags were 33-65% lower following 24 hours of storage. These results indicate that significant odorant bias may occur when using Tedlar bags for the sampling of odors from animal production facilities.

Last Modified: 10/25/2014
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