|Cole, Noel - Andy|
Submitted to: Sensors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2010
Publication Date: 9/13/2010
Citation: Parker, D.B., Perschbacher-Buser, Z.L., Cole, N.A., Koziel, J.A. 2010. Recovery of agricultural odors and odorous compounds from polyvinyl fluoride film bags. Sensors. 10:8536-8552. DOI: 10.3390/s100908536 Interpretive Summary: Odor is produced at livestock operations when chemical compounds are emitted from manure and wastewater sources. One method for assessing odor is to collect air samples in plastic bags and have those samples analyzed in the laboratory by trained human panelists. Most researchers and regulatory personnel in the U.S. use bags made of polyvinyl fluoride (PVF) film for collection of odor samples. In this study, we simultaneously assessed the recoveries of odor and the chemical compounds responsible for odor in PVF bag samples. Two bag types, commercial bags and homemade bags, were used to measure chemical and odor recoveries at sample holding times ranging from 1 hour to 7 days. Only 2 to 40% of the chemical compounds were recovered after being stored in the bag for 1 hour, and only 0 to 14% were recovered after 7 days. Between 1 hour and 7 days, odor concentrations increased in commercial bags and decreased in homemade bags. Minimal changes were observed in the overall character and offensiveness of the odor over the same time period. These results show that storing odor samples in PVF bags results in a large reduction of the specific chemical compounds over time, but the effect on odor concentration is not as dramatic. Because of this sampling bias, researchers and practitioners are cautioned to account for the losses in odorous compounds when using PVF bags for quantification of odor or those chemicals responsible for odor.
Technical Abstract: Accurate sampling methods are necessary when quantifying odor and volatile organic compound emissions at agricultural facilities. The commonly accepted methodology in the U.S. has been to collect odor samples in polyvinyl fluoride bags (PVF, brand name Tedlar®) and, subsequently, analyze with human panelists using dynamic triangular forced-choice olfactometry. The purpose of this research was to simultaneously quantify and compare recoveries of odor and odorous compounds from both commercial and homemade PVF sampling bags. A standard gas mixture consisting of p-cresol (40 µg m**-**3) and seven volatile fatty acids: acetic (2,311 µg m**-**3), propionic (15,800 µg m**-**3), isobutyric (1,686 µg m**-**3), butyric (1,049 µg m**-**3), isovaleric (1,236 µg m**-**3), valeric (643 µg m**-**3), and hexanoic (2,158 µg m**-**3) was placed in the PVF bags at times of 1 h, 1 d, 2 d, 3 d, and 7 d prior to compound and odor concentration analyses. Compound concentrations were quantified using sorbent tubes and gas chromatography/mass spectrometry. Odor concentration, intensity, and hedonic tone were measured using a panel of trained human subjects. Compound recoveries ranged from 2 to 40% after 1 h and 0 to 14% after 7 d. Between 1 h and 7 d, odor concentrations increased by 45% in commercial bags, and decreased by 39% in homemade bags. Minimal changes were observed in intensity and hedonic tone over the same time period. These results suggest that PVF bags can bias individual compound concentrations and odor as measured by DTFCO.