Oil source-fingerprinting is an environmental forensics technique that uses analytical chemistry to determine the origin of oil residues in environmental samples by comparison to a known or suspected source oil. Currently, the only standardized method for oil source fingerprinting is a qualitative approach that is very effective in almost every oil spill response situation. However, the need for quantitative oil source-fingerprinting methods to complement the qualitative determinations is extremely desired. The research herein aims to utilize data generated by gas chromatography/mass spectrometry (GC/MS) methodologies to test two different quantitative techniques: diagnostic biomarker ratio analysis and chemometrics. The most common crude oil constituents used for oil source-fingerprinting are the oil biomarker compounds. Oil biomarkers are polycyclic aliphatic hydrocarbon molecules typically resistant to environmental weathering (i.e., biological and physiochemical transformations). They are universal in crude oils and most petroleum products, and impart unique ratios in oils of different maturities and geographic sources. Diagnostic biomarker ratio analysis will be used to establish a suite of diagnostic biomarker ratios with statistical limitations that can differentiate oil from the Deepwater Horizon oil spill, or Macondo 252 (MC252) oil, from other South Louisiana crude oils. This technique is not limited to MC252 oil. Diagnostic ratios can be determined and tested for any source oil. Current published research has documented weathering of several of the biomarker compounds used for oil source-fingerprinting. Any weathering of MC252 oil residues in the environment will adversely affect the diagnostic biomarker ratio analysis. Therefore, a more advanced quantitative technique, chemometrics, will use pattern recognition algorithms to determine the innate similarity of environmental oil residues to MC252 oil
