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The current well-established chromatography and mass spectrometry based oil spill identification procedures, such as those outlined by the European Committee for Standardization, are highly reliable as methods, highly defensible in the court of law, and widely applicable to the majority of oil spill situations. Nevertheless, the methodology is time consuming and labour intensive, which may not be ideal when dealing with an emergency oil spill situation. In this study, direct analysis in real time time-of-flight mass spectrometry (DART/TOFMS) was used to successfully develop an efficient oil identification method. To confirm the accuracy of this method spilled oil samples were tested from five previous years of blind round robin testing organized by the oil spill identification network of experts (OSINET) under the Bonn Agreement. Heatmap inspection, principal component analysis and finally discriminant analysis of principal components were used to arrive at final predictions regarding the identities of the spilled oil samples. The results were compared with the results of previous gas chromatography flame ionization detection (GC/FID) and gas chromatography triple quadrupole mass spectrometry (GC/MS/MS) analyses of the same oils. While taking only about a tenth of the time, the DART/TOFMS analysis produced results similar to those of classical GC/FID and GC/MS/MS (EI + ) procedures. The ability of DART/TOFMS to display this level of validity exemplifies its potential to be a new tool for supplementing classical analyses for oil spill forensics.

Spilled crude oil samples contain various toxic compounds including polycyclic aromatic hydrocarbons (PAHs) as well as sulfur heterocycles (PASHs) and their related alkylated forms (APAHs and APASHs). In this study, a method was successfully developed employing a gas chromatography quadrupole time-of-flight (GC-QToF) mass spectrometer to quantitatively analyze both PAHs/APAHs and PASHs/APASHs in these samples. With GC-QToF, the monoisotopic mass of the compounds is distinguished, allowing the PASHs/APASHs to be extracted separately from the PAHs/APAHs in crude oil. A gas chromatography triple quadrupole (GC-MS/MS) mass spectrometer was also used to confirm that a GC-QToF is the preferred instrument for analyzing these compounds. With the use of PASH/APASH standards to determine response correction factors (RCFs) in relation to PAH standards, the developed method is capable of analyzing PAHs, APAHs, PASHs, and APASHs in a single injection. The use of RCFs allowed for the development of a practical polycyclic aromatic carbon (PAC) method for analyzing a total of 77 compounds of the 2 groups in crude oil. This newly developed method was applied to spilled crude oils, demonstrating its potential in toxicological study as well as oil spill forensic investigation.

Frequent small-scale environmental releases of lubricating (lube) oils have deleterious effects on aquatic ecosystems. In the event of a spill, oil fingerprinting is critical to source attribution, clean-up procedures, and liability assignment. Oil forensic investigations are particularly challenging when oils are weathered over an extended period of time, as a large number of biomarkers become lost and the chemical composition changes significantly from its source. This study simulated an environmental case in which long-term weathered lube oil "spill" samples were matched to unweathered suspect "source" oils. While traditional oil fingerprinting techniques including GC/FID and GC/MS diagnostic ratios were insufficient for reliably attributing the source, a comprehensive and systematically tiered approach proved successful. The proposed methodology featured three tiers: Tier 1 GC/FID, Tier 2 GC/MS diagnostic ratios, and Tier 3 multivariate statistics. This novel approach provided environmental chemists with a powerful tool for dealing with an otherwise extremely challenging lube oil forensic investigation.