DIFFERENTIATION OF THE SOURCE OF SPILLED OIL AND MONITORING OF THE OIL WEATHERING PROCESS USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY

Methods described use high-performance capillary gas chromatography-mass spectrometry (CC-MS) operating mainly in the selected-ion monitoring (SIM) mode for oil analysis. The methods have been applied to the characterization of crude oils, weathered oils, biodegradation oils, and oil-spill-related environmental samples with different compositions, nature, and concentrations. Using CC-MS enables the identification and quantitation of specific target petroleum hydrocarbons including C-8 through C-40 normal alkanes, the isoprenoids, BTEX and alkyl benzene, target polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues, and biomarker triterpanes and steranes. The analysis of these target compounds and/or compound groups is important and essential for oil-spill monitoring. The analytical data have been successfully used for the differentiation of oils, tracking the source of long-term spilled oils, monitoring the oil weathering and biodegradation process under variable environmental conditions, and the determination of the weathering percentages of very heavily weathered oil samples by the selective use of biomarker parameters. Compared to some other traditional methods which were originally designed for industrial waste and hazardous waste, the methods described here are more selective and give a better representation of the true oil composition, and hence are more defensible.