A comparison of the acidic and basic extracts of oil sands process water (OSPW) was performed using positive- and negative-ion electrospray ionization (ESI) and atmospheric pressure photoionization (APPI), coupled with a 12 T solariX Fourier transform ion cyclotron resonance mass spectrometer (FTICR MS). In general, the acid-neutral extracts showed higher oxygen content within the negative-ion profiles (both APPI and ESI). The hydrocarbon class was readily observed in the base-neutral extract. Furthermore, a comparison of O2S (radical ion) and O2S [H] (protonated) classes in positive-ion APPI data showed significant differences in the distribution of double-bond equivalent (DBE) versus carbon number, which are indicative of differences in structures of the two classes. The S-containing species were relatively more abundant in the base-neutral extract, and the radical O2S ions displayed the characteristic profile of thiophenic compounds. ESI profiles for samples extracted at both pH values (2 and 11) investigated were suitable for characterization of the most polar components within the complex OSPW mixture, while APPI was suitable for the ionization of a broader range of heteroatom classes. Because profile comparisons are important for environmental forensics, this study highlights the need for careful attention to extraction pH effects on the measured profiles of OSPW components.

•Use of LDI mass spectrometry to study petroleum is known to present challenges.•Vacuum residues and their fractions were studied using LDI mass spectrometry.•Under careful conditions, reliable average molecular weights were determined.•The data was used to statistically classify the samples.•The results can be correlated with physical properties, such as density.Average molecular weight analysis of vacuum residues using laser desorption ionization (LDI) can be a difficult task due to the significant influence of the experimental parameters and gas-phase reactions. In this paper, laser desorption/ionization time-of-flight mass spectrometry in reflectron mode (LDI TOF MS) was used to analyze vacuum residues and their molecular distillations (MD) fractions obtained at distillation cuts of 510–603 °C, 510–645 °C and 510–687 °C. Those samples associated with the lowest distillation temperature presented the narrowest molecular weight distributions and lowest average molecular weight (Mw) indicating lower complexity. American Petroleum Institute gravity, or API gravity (API°), is a measure of the weight of liquid petroleum compared to water, as expected a correlation between Mw and API° was determined, where lower API° correlated with higher molecular weight. When using higher laser energies mass spectra were acquired with a spacing of 24 Da between the peaks, indicating the production of carbon clusters or “fullerenes”. This suggests that asphaltenes could be the precursors of the clusters that extend over 2500 Da in reflectron mode. Under appropriate experimental conditions, it was possible to produce repeatable molecular distribution for all the samples. Likewise, mass spectrometric data can be used in Principal Component Analysis (PCA) and Partial Least Square (PLS) analysis to discriminate and to predict density of the samples with low percentage of errors.

There is a growing need for environmental screening of natural waters in the Athabasca region of Alberta, Canada, particularly in the differentiation between anthropogenic and naturally-derived organic compounds associated with weathered bitumen deposits. Previous research has focused primarily upon characterization of naphthenic acids in water samples by negative-ion electrospray ionization methods. Atmospheric pressure photoionization is a much less widely used ionization method, but one that affords the possibility of observing low polarity compounds that cannot be readily observed by electrospray ionization. This study describes the first usage of atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (in both positive-ion and negative-ion modes) to characterize and compare extracts of oil sands process water, river water, and groundwater samples from areas associated with oil sands mining activities. When comparing mass spectra previously obtained by electrospray ionization and data acquired by atmospheric pressure photoionization, there can be a doubling of the number of components detected. In addition to polar compounds that have previously been observed, low-polarity, sulfur-containing compounds and hydrocarbons that do not incorporate a heteroatom were detected. These latter components, which are not amenable to electrospray ionization, have potential for screening efforts within monitoring programs of the oil sands.

The change in profile of crude oil following a release into the environment is a topic of significant interest, and there is a need to develop analytical methodologies for understanding natural processes which affect related complex mixture profiles. One such process is the exposure to sunlight. In the following investigation, three oil samples were studied: one served as a control, a second was subjected to irradiation by an ultraviolet lamp, and a third sample was irradiated by a SoLux light source which closely models the solar emission profile. The usage of the SoLux light source represents a new method which enables a controlled experiment to mimic the effects of sunlight upon the sample. Atmospheric pressure photoionization was selected as the primary ionization method due to the ability to ionize a broad range of compounds, including low polarity components which could not be observed using electrospray ionization. During a test of sample preparation methods, the addition of a protic cosolvent to the sample solutions was shown to broaden the range of heteroatom-containing components observed. Following characterization, it was found that the polyaromatic hydrocarbons did not change in profile, while compounds containing a heteroatom exhibited a tendency to oxidize following photoirradiation. Sulfur-containing compounds with a low number of double bond equivalents were among the most reactive components of the complex mixture. The photooxidation of compounds in petroleum, following exposure to sunlight, is expected to have significance with regards to solubility and potential toxicity.

The Athabasca oil sands industry, an alternative source of petroleum, uses large quantities of water during processing of the oil sands. In keeping with Canadian environmental policy, the processed water cannot be released to natural waters and is thus retained on-site in large tailings ponds. There is an increasing need for further development of analytical methods for environmental monitoring. The following details the first example of the application of gas chromatography atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FTICR MS) for the study of environmental samples from the Athabasca region of Canada. APCI offers the advantages of reduced fragmentation compared to other ionization methods and is also more amenable to compounds that are inaccessible by electrospray ionization. The combination of GC with ultrahigh resolution mass spectrometry can improve the characterization of complex mixtures where components cannot be resolved by GC alone. This, in turn, affords the ability to monitor extracted ion chromatograms for components of the same nominal mass and isomers in the complex mixtures. The proof of concept work described here is based upon the characterization of one oil sands process water sample and two groundwater samples in the area of oil sands activity. Using the new method, the Ox and OxS compound classes predominated, with OxS classes being particularly relevant to the oil sands industry. The potential to resolve retention times for individual components within the complex mixture, highlighting contributions from isomers, and to characterize retention time profiles for homologous series is shown, in addition to the ability to follow profiles of double bond equivalents and carbon number for a compound class as a function of retention time. The method is shown to be well-suited for environmental forensics.

The Athabasca oil sands in Canada are a less conventional source of oil which have seen rapid development. There are concerns about the environmental impact, with particular respect to components in oil sands process water which may enter the aquatic ecosystem. Naphthenic acids have been previously targeted for study, due to their implications in toxicity toward aquatic wildlife, but it is believed that other components, too, contribute toward the potential toxicity of the oil sands process water. When mass spectrometry is used, it is necessary to use instrumentation with a high resolving power and mass accuracy when studying complex mixtures, but the technique has previously been hindered by the range of compounds that have been accessible via common ionization techniques, such as electrospray ionization. The research described here applied Fourier transform ion cyclotron resonance mass spectrometry in conjunction with electrospray ionization and atmospheric pressure photoionization, in both positive-ion and negative-ion modes, to the characterization of oil sands process water for the first time. The results highlight the need for broader characterization when investigating toxic components within oil sands process water.

Fourier transform ion cyclotron resonance mass spectrometry has made a significant contribution to the characterization of naphthenic acids in petroleum samples. The characterization of naphthenic acids is of particular interest due to their believed involvement in corrosion and deposit formation, as well as their toxicity toward aquatic organisms. Analysis of a complex mixture, such as a petroleum sample, can present challenges in terms of data analysis and visualization. A variety of graphical methods for representing the data are evaluated, and the use of a heat map, a method primarily used within molecular biology, is highlighted. An Athabasca oil sands sample was characterized and compounds of the empirical formula CnH2n+zOx, where x = 2−5, were observed. The range of oxygen content is of particular relevance in light of other research, which has shown that the total acid number of a petroleum sample is not a reliable method for evaluating the acid content, as not all of the acids are monoprotic.

Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has become increasingly significant within recent years. The inherently ultra-high resolution and mass accuracy allow unequivocal assignments of chemical formulae to be made and further structural elucidation can be conducted through the utilization of tandem mass spectrometry techniques. With the advent of electrospray ionization (ESI), FT-ICR mass spectrometry has become a powerful tool for the investigation of biological macromolecules, such as the study of non-covalent interactions of proteins. In this article, the basic principles are highlighted, some of the techniques employed are described and examples of applications are provided, with particular respect being paid to the field of characterization of biomolecules.

Naphthenic acids present formidable challenges for the petroleum industry and are a growing concern in the aquatic environment. For example, these acids are responsible for corrosion of refinery equipment, leading to the incurrence of additional costs to the consumer, and are toxic to aquatic wildlife, making disposal and remediation of contaminated waters and sediments a significant problem. The detection and characterization of naphthenic acids is therefore of considerable importance. Fourier transform ion cyclotron resonance mass spectrometry is presented as a technique with inherently ultra-high mass accuracy and resolution, affording unequivocal assignments. The suitability of the technique for environmental applications is demonstrated to characterize two different commercial mixtures of naphthenic acids and one oilsands tailings pond sample.