Forensic characterization of mid-range petroleum distillates using light biomarkers

Due to oil refining, commonly used higher boiling biomarkers for oil-source correlation are absent from mid-range petroleum distillates, while lighter biomarkers are concentrated in such products. This study evaluated 63 diagnostic ratios of light biomarkers such as bicyclic sesquiterpanes, diamondoids, and lighter aromatic compounds using 70 diesel oil samples obtained from three Swedish refineries and local gas stations, mostly over a six-month period in 2015. On the basis of their diagnostic power and partial correlation coefficients, a set of 24 ratios is suggested for oil-source correlation of lighter products. The frequency of false positives for this set was determined to be approximately 0.1%. It should be emphasized that in the event of an oil spill, diesel oils are rapidly influenced by weathering and many of the ratios will be affected.