Examination of GC-MS chromatograms of bicyclic biomarker sesquiterpanes and diamondoids using their characteristic fragment ions provides another highly diagnostic means for correlation and differentiation of unknown spilled oil samples that are difficult to identify by current fingerprinting techniques. In this work, GC-FID and GC-MS fingerprinting analysis in conjunction with statistical data analysis of target oil hydrocarbons including sesquiterpanes and diamondoids was performed for identification of an unknown oil spill incident occurred in a harbor of the Netherlands in 2004. Forensic investigation included the: (1) identification and characterization of numerous sesquiterpanes and diamondoids; (2) comparison of the distribution of sesquiterpanes and diamondoids; (3) development of a series of diagnostic indices for correlation and differentiation of spilled fuel samples; and (4) use of “Two-tailed” unpaired Student'S t-test to statistically evaluate the imperceptible differences between the selected diagnostic ratios of target compounds in the spill fuel and the suspected source fuel samples. At a 95% confidence interval, 33 of all 38 diagnostic indices (among them, 20 are diagnostic indices of sesquiterpanes and diamondoids) show positive matches between spill sample and suspected source fuel sample 1. In comparison, only 5 of 38 diagnostic indices indicate positive matches between spill sample and suspected source sample 3. These evidences demonstrate that the bunker ship has the responsibility for this oil spill incident.

Observations made for the analysis of the oil spill dispersant tracer dioctyl sulfosuccinate (DOSS) during LC50 toxicity testing, highlighted a stability issue for this tracer compound in seawater. A liquid chromatography high-resolution quadrupole time-of-flight mass spectrometry (LC/QToF) was used to confirm monooctyl sulfosuccinate (MOSS) as the only significant DOSS breakdown product, and not the related isomer, 4-(2-ethylhexyl) 2-sulfobutanedioate. Combined analysis of DOSS and MOSS was shown to be applicable to monitoring of spill dispersants Corexit® EC9500A, Finasol OSR52, Slickgone NS, and Slickgone EW. The unassisted conversion of DOSS to MOSS occurred in all four oil spill dispersants solubilized in seawater, although differences were noted in the rate of MOSS formation. A marine microcosm study of Corexit EC9500A, the formulation most rapid to form MOSS, provided further evidence of the stoichiometric conversion of DOSS to MOSS under conditions relevant to real world dilbit spill. Results supported combined DOSS and MOSS analysis for the monitoring of spill dispersant in a marine environment, with a significant extension of sample collection time by 10 days or longer in cooler conditions. Implications of the unassisted formation of MOSS and combined DOSS:MOSS analysis are discussed in relation to improving dispersant LC50 toxicity studies.