Identification of plant-based spilled oils using direct analysis in real-time–time-of-flight mass spectrometry with hydrophobic paper sampling

Spilled plant-based oils behave very differently in comparison to petroleum oils and require different clean-up measures. They do not evaporate, disperse, dissolve, or emulsify to a significant degree but can polymerize and form an impermeable cap on sediment, smothering benthic media and resulting in an immediate impact on the wildlife community. The current study explored the application of rapid up-to-date direct analysis in real time (DART) with high-resolution mass spectrometry for plant-based oil typing. The study introduced a new concept of using hydrophobic paper to collect and analyze oil samples, thus minimizing sample preparation and expenses. Application of this technique showed its ability to speedily distinguish plant-based from petroleum-based oils. A microcosm experiment exposing plant-based oil samples to weathering processes for comparison with petroleum-based oils demonstrated the ability of the method to classify weathered oil samples and identify their source oil. It was observed that canola and peanut oil were the most resistant to weathering processes. The developed DART-TOFMS method was shown to be accurate for short-term weathered oil spills up to between 12 and 26 days of exposure. The developed method performed identification in less than a day compared to the established multi-day method for oil spill forensics requiring careful sample collection in glass containers, time-consuming laboratory clean-up, lengthy gas chromatography sequences, and careful integration including integration of retention time markers.