Correlation of weathered and unweathered oil samples using the carbon isotopic composition of individual components in the crude oil

摘要

Once a crude oil is spilled in the environment, changes to the composition of the spilled oil will occur. Evaporation and water washing cause the initial changes, followed by photo-oxidation and biodegradation. Correlations between spilled oils and suspected sources are normally based on techniques such as gas chromatography (GC) and gas chromatography-mass spectrometry (GCMS). Whilst generally successful, heavily weathered residues or refined products are often extremely difficult to correlate by GC or GCMS. In this paper results from a relatively new correlation technique, gas chromatography-isotope ratio mass spectrometry (GCIRMS) are discussed. GCIRMS permits the determination of the isotopic composition of individual components in complex mixtures. The isotopic composition of individual compounds is relatively unaffected by the effects of biodegradation. GCIRMS is particularly powerful for refined products which contain none of the biomarkers commonly used for correlation purposes. GCIRMS data can be utilized in conjunction with the conventional techniques and the end result is a powerful tool that has widespread applicability for monitoring and correlation studies.