Stability of Odorants from Pig Production in Sampling Bags for Olfactometry

Abstract

Odor from pig production facilities is typically measured with olfactometry, whereby odor samples are collected in sampling bags and assessed by human panelists within 30 h. In the present study, the storage stability of odorants in two types of sampling bags that are often used for olfactometry was investigated. The bags were made of Tedlar or Nalophan. In a field experiment, humid and dried air samples were collected from a pig production facility with growing-finishing pigs and analyzed with a gas chromatograph with an amperometric sulfur detector at 4, 8, 12, 28, 52, and 76 h after sampling. In a laboratory experiment, the bags were filled with a humid gas mixture containing carboxylic acids, phenols, indoles, and sulfur compounds and analyzed with proton-transfer-reaction mass spectrometry after 0, 4, 8, 12, and 24 h. The results demonstrated that the concentrations of carboxylic acids, phenols, and indoles decreased by 50 to >99% during the 24 h of storage in Tedlar and Nalophan bags. The concentration of hydrogen sulfide decreased by approximately 30% during the 24 h of storage in Nalophan bags, whereas in Tedlar bags the concentration of sulfur compounds decreased by <5%. In conclusion, the concentrations of odorants in air samples from pig production facilities significantly decrease during storage in Tedlar and Nalophan bags, and the composition changes toward a higher relative presence of sulfur compounds. This can result in underestimation of odor emissions from pig production facilities and of the effect of odor reduction technologies.

Investigation of Volatiles Emitted from Freshly Cut Onions (Allium cepa L.) by Real Time Proton-Transfer Reaction-Mass Spectrometry (PTR-MS)

“…The limit of detection (LOD, calculated as three times the standard deviation on blank samples) of our PTR-MS system with respect to volatile organic sulfur compounds is typically in the range of 0.02–0.15 ppb [25–27], which is lower than LOD of some alternative methods, e.g., GC-PFPD (pulsed flame photometric detector) (0.5–2.4 ppb, three times the standard deviation) [28] and GC-ASD (amperometric sulfur detector) (around 5 ppb) [29]. However, the LOD of the PTR-MS used in this study is higher than found for GC-ToF-MS (0.122 ppt, three times the standard deviation of the background noise) [30], and the method detection limit (MDL) is often expected to be much higher than the LOD [30].…”

Recovery of Odorants from an Olfactometer Measured by Proton-Transfer-Reaction Mass Spectrometry

“…It has previously been shown that the concentration of several typical odorants from animal houses (reduced sulfur compounds, amines, carboxylic acids, phenols and indoles) decreases during the storage in one or more types of sampling bags, possibly due to sorption to the bag material and diffusion out of the bags [2–6]. For certain compounds, e.g., phenols, the 24 h recovery is <10% [3,4,6]. …”

Evaluation of the performance of field olfactometers by selected ion flow tube mass spectrometry

“…The odorous gas is typically collected, employing the lung principal, in tetrafluoroethylene hexafluoropropylene (FEP), polyvinyl fluoride (PVF, Tedlar) or polyethylene terepthalate (PET, Nalophan) sampling bags (Trabue, Kerr, Bearson, & Ziemer, 2011;Zhang et al, 2010). Odorous compounds may adsorb on the sampling bag surface or diffuse through the bag during storage or transport (Hansen, Adamsen, Feilberg, & Jonassen, 2011). This results in a sample that might be different in chemical composition when compared to the sample from which the odour had to be evaluated (van Harreveld, 2003).…”