Exploring canine olfactory generalization using odor profile fractions from native crude oils

Canines are used by both government agencies and industries for their keen olfactory capability as well as selectivity, reliability, versatility, and speed. Within the last decade, canines have been used for the detection of on-shore crude oil. They were previously shown to find these deposits with high accuracy, providing increased confidence with little risk to oil spill response survey teams. In order to efficiently train canines, it is important to understand the odorants or groups of odorants that such canines use when locating subsurface crude oil deposits, as well as track how the odorant profile changes as the crude oil undergoes degradation. In this study, headspace solid phase microextraction (HS-SPME) was used in combination with gas chromatography-mass spectrometry (GC-MS) to extract and separate odorants from the headspace of various crude oils. After, eluent fractions of the crude oil odor profile were separated and collected onto sorbent materials, which were then used as canine testing probes in a series of trials. These probes, along with negative and positive controls were presented to three previously-trained and operational crude oil detection canines. Three eluent fractions of both fresh and weathered samples were presented, resulting in a 100% response rate from the canines on all three fractions from both the fresh and weathered samples. These results indicated that canines are capable of detecting crude oil from any fraction of the odor profile demonstrating the potential of the canines to generalize across a variety of crude oils and stages of weathering.