Two samples of petroleum may look identical—but at the chemical level, their differences become apparent. Each sample has a chemical “fingerprint” that provides important clues to its origin. Battelle is nearing completion on a new study to characterize additional biomarkers for more accurate identification and attribution of crude oils and refined hydrocarbon fuels. With these additions, Battelle is now able to provide the most comprehensive hydrocarbon analysis and characterization available on the market today.
Battelle has expanded their hydrocarbon forensic toolkit to include additional classes of biomarkers including sesquiterpanes, adamantanes, diamantanes, monoaromatic steranes and selected alkyl cyclohexanes. Adding these biomarkers will allow researchers to perform more accurate and nuanced source attribution and provide new insights into how hydrocarbons change during refining, weathering or processing.
Using the additional biomarkers as well as traditional biomarkers (e.g. steranes, diasteranes, hopanes and triaromatic steranes), Battelle researchers have now analyzed 79 samples from around the world, including both raw crude oil and petroleum distillate examples. They also looked at natural coal formations and manufactured gas plant byproducts such as coal tar and creosote. The results will be used to create a “reference library” of chemical fingerprints that can be used for source attribution.
Hydrocarbon fingerprinting analyzes the chemical makeup of a sample to look for the presence and ratios of certain organic compounds. Crude oils contain hydrocarbon chains of various lengths as well as other organic compounds. These compounds act as biomarkers that help researchers distinguish between hydrocarbons from different sources; two samples with the same chemical fingerprint are highly likely to be from the same source. Hydrocarbon forensics uses these biomarkers to determine, for example, whether oil found in the environment is a result of nearby development activities or comes from other sources. It can also be used to apportion responsibility in a site contaminated by hydrocarbons and hydrocarbon byproducts from multiple sources.
As hydrocarbons are refined, their chemical fingerprints change as hydrocarbons of different molecular weights are separated and volatile organics are distilled out. Weathering also changes the chemical fingerprint. This can make it difficult to backtrack from a weathered sample, refined fuel or byproduct to its original crude source. Different biomarkers may be more useful for source attribution of refined fuels or byproducts.
Battelle’s expanded analytical toolkit and database will facilitate more accurate attribution of a wide range of crudes, refined fuels and hydrocarbon byproducts. The database will provide a starting place for comparison of new samples so chemists can determine what additional tests will be needed for definitive identification.