STUDY OF 22-YEAR-OLD ARROW OIL SAMPLES USING BIOMARKER COMPOUNDS BY GC/MS

A GC/MS method for the characterization of 22-year-old spilled Arrow oil is described. After 22 years of weathering in the environment, most saturated hydrocarbons and polycyclic aromatic hydrocarbons in most Arrow oil samples have been lost. Their fingerprints give little information of the source, characteristics, and fate of the spilled oil. However, the method using biomarker compounds by GC/MS offers the distinct advantages of being better able to withstand interference from heavy weathering effects and to identify and match the spilled oil source. From 11 intertidal sediment samples collected from the shorelines of Chedabucto Bay, 47 triterpanes and steranes were positively identified. The relative abundance ratios of several pairs of triterpane and sterane compounds, especially the ratio of C-29/C-30 hopanes that are displayed as major peaks in the m/z 191 ion chromatograms, are apparently independent of weathering effects and are unambiguously used for identifying the source of the 22-year-old Arrow oil samples.