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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.

A direct injection liquid chromatography tandem atmospheric pressure chemical ionization mass spectrometry method was developed for the determination of diethylene glycol methyl ether (DEGME), dipropylene glycol butyl ether (DPGBE), and dipropylene glycol methyl ether (DPGME). This aqueous based method is suitable for many different applications, but was specifically applied to wood stains in the present study. Multiple reaction monitoring (MRM) mode was employed to quantify the glycol ethers by detection of the precursor to product transitions at 121.1 m/z→ 59.1 m/z(DEGME), 191.1 m/z→ 59.1 m/z(DPGBE), and 149.1 m/z→ 59.1 m/z(DPGME). Secondary qualifier ion transitions were used to confirm identity, and the daidzein internal standard demonstrated an excellent correlation to glycol ether responses. Method linearity by (1/x) linear weighted regression showed coefficients ≥ 0.995 in the ranges 0.5 ng mL−1to 25 ng mL−1, 2.5 ng mL−1to 50 ng mL−1, and 5.0 ng mL−1to 50 ng mL−1for DEGME, DPGBE, and DPGME respectively. A precision of <5% relative standard deviation was demonstrated for quality control samples, which showed excellent accuracy in the recovery of analytes from blind quality assurance samples. The method was proven to be robust and consistent during analysis of eight different commercially available wood stains. All tested wood stains contained <0.002% (w/w) DEGME, verifying compliance with the current Canadian Environment Protection Act of 1% w/w limit in surface coating products. In contrast, significant amounts of DPGBE and DPGME were found in six different woodstains. The presence of propylene glycol ethers in wood stain products is discussed.

A simplified liquid–liquid micro-extraction (LLME) GC/MS/MS method was developed for the determination of 18 polycyclic aromatic hydrocarbons (PAHs) in surface water. This method utilizes a pseudo multiple reaction monitoring (PMRM) mode, a technique in which the third quadrupole monitors the same m/zas for the first quadrupole precursor ion. The use of helium as the only collision gas improved the sensitivity by significantly reducing both PAH compound fragmentation and baseline noise. For PAH determination, the PMRM approach proved superior to the classical quadrupole MRM technique in terms of enhanced sensitivity. With observed improvements in sensitivity, micro-extraction using only 4 mL of a novel binary solvent became possible, with corresponding reduction in time consuming sample preparation procedures and toxic solvent usage. Quantifying and qualifying ions, in addition to retention times, were used to verify trace level PAHs. During method validation, the limit of quantitation (LOQ) in surface water was observed to be 10 ng L−1for the target PAHs. The recovery of individual PAHs was in the range of 80 to 114% from a water matrix, with a corresponding precision between 1.4 and 4.8% RSD. The robustness and accuracy of this method was demonstrated by its success in repeated proficiency test studies. The procedure has been successful during routine use in environmental sample testing and analysis of chemically enhanced water accommodated fraction (CEWAF) samples from toxicological LC50 (50% lethal concentration) bioassays, showing its applicability to situations in which both crude oil and oil spill dispersants are present.

A micro-extraction gas chromatography pseudo-MRM mass spectrometry method was developed for the rapid determination of 50 selected polycyclic aromatic hydrocarbons (PAHs) and alkylated-PAHs (APAHs) in seawater. The combined PAHs and APAHs, referred to as total polycyclic aromatic hydrocarbons (TPAHs), include dibenzothiophenes and naphthabenzothiophenes. The method was aimed at the assessment of TPAH compounds in the water accommodated fraction of oil in seawater, now promoted for use in toxicity evaluation following an oil spill incident. The presented method applies a unique multi-level quantitative calibration method for many alkylated PAHs for which the authentic standards are either extremely expensive or difficult to obtain. This new method was able to determine all 50 TPAH compounds while avoiding excessive cost. The reliability of this isotope dilution micro-extraction method was shown by extraction and analysis of Prudhoe Bay oil, with comparable compound results corresponding to published data. The developed method was successfully applied to water accommodated fraction (WAF) samples prepared with Low Sulfur Marine Diesel, High Sulfur Fuel Oil and Diluted Bitumen in seawater. With reduced cost and a single injection for all the 50 target compounds, this rapid quantitative method allows for routine environmental monitoring of a larger suite of TPAH analytes.