Field air sampling and simultaneous chemical and sensory analysis of livestock odorants with sorbent tubes and GC-MS/olfactometry

Characterization and quantification of livestock odorants is one of the most challenging analytical tasks because odor-causing chemicals are very reactive, polar, and often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this research was to develop a novel analytical method for characterization of the livestock odorants including their odor character, odor intensity, and hedonic tone and to apply this method for quantitative analysis of the key odorants responsible for livestock odor. Field samples were collected with sorbent tubes packed with Tenax TA. The automated one-step thermal desorption module coupled with multidimensional gas chromatography-mass spectrometry/olfactometry system was used for simultaneous chemical and odor analysis. Fifteen odorous VOCs identified from livestock operations were quantified. Method detection limits ranged from 30 pg for indole to 3590 pg for acetic acid per sample. In addition, odor character, odor intensity, and hedonic tone associated with each of the target odorants were also analyzed simultaneously. The mass of each VOC in the sample correlated well with the log stimulus intensity of odor. All of the coefficients of determination (R²) were greater than 0.74, and the top 10 R²s were greater than 0.90. Field air samples from swine and dairy operations confirmed that target compounds quantified represented typical odor-causing compounds emitted from livestock.