Characterization of oil sands naphthenic acids by negative-ion electrospray ionization mass spectrometry : influence of acidic versus basic transfer solvent

Considerable effort and progress has been made over the past decade with respect to development of analytical tools for the determination of naphthenic acids and related components in environmental samples. However, experimental variables that influence the analytical results have not been fully explored. The relative contributions of Ox classes are of particular interest in data obtained using negative-ion electrospray ionization mass spectrometry. Using two types of ultrahigh resolution mass spectrometers (Orbitrap and FT-ICR), the apparent pH of the transfer solvent was observed to have a significant impact upon compound class distributions. A basic transfer solvent favored the detection of Ox species of lower oxygen content, while acidic pH favored the preferential observation of organic compounds with higher oxygen contents. These observed trends were independent of the instrument type. In addition, when using an acidic transfer solvent, the overall observed response was reduced by a factor of ∼20. Thus, the apparent pH of the transfer solvent has critical influence upon detection and upon the profile of different components observed within a complex mixture. In turn, this significantly impacts oil sands environmental monitoring for toxicity, forensic interpretation, and quantitation; when comparing data sets from different laboratories, these findings should therefore be taken into account

Petroleomic analysis of the treatment of naphthenic organics in oil sands process-affected water with buoyant photocatalysts

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.watres.2018.05.011 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/The persistence of toxicity associated with the soluble naphthenic organic compounds (NOCs) of oil sands process-affected water (OSPW) implies that a treatment solution may be necessary to enable safe return of this water to the environment. Due to recent advances in high-resolution mass spectrometry (HRMS), the majority of the toxicity of OSPW is currently understood to derive from a subset of toxic classes, comprising only a minority of the total NOCs. Herein, oxidative treatment of OSPW with buoyant photocatalysts was evaluated under a petroleomics paradigm: chemical changes across acid-, base- and neutral-extractable organic fractions were tracked throughout the treatment with both positive and negative ion mode electrospray ionization (ESI) Orbitrap MS. Elimination of detected OS+ and NO+ classes of concern in the earliest stages of the treatment, along with preferential degradation of high carbon-numbered O2− acids, suggest that photocatalysis may detoxify OSPW with higher efficiency than previously thought. Application of petroleomic level analysis offers unprecedented insights into the treatment of petroleum impacted water, allowing reaction trends to be followed across multiple fractions and thousands of compounds simultaneously.Natural Sciences and Engineering Research Council of CanadaNSERC Vanier Canada Graduate ScholarshipOntario Graduate Scholarshi

Solubilized Chitosan Biopolymers for Sequestration of Organic Acids in Aquatic Environments after Biodegradation in a Constructed Wetland Treatment System

Pristine chitosan was dissolved in two different respective aqueous acids, namely acetic acid (AcA) and hydrochloric acid (HCl). The respective acid solutions were used as media to associate with naphthenic acid fraction compounds (NAFCs) from raw oil sands process water (R-OSPW) contaminants and constructed treatment wetland systems OSPW (CWTS-OSPW) samples. The results revealed selective removal of NAFCs and lyotropic effects due to variable counterion binding of chloride versus acetate with the ionized NAFCs (carboxylate species)

Advances in Distinguishing Groundwater Influenced by Oil Sands Process-Affected Water (OSPW) from Natural Bitumen-Influenced Groundwater

The objective of this study was to advance analytical methods for detecting oil sands process-affected water (OSPW) seepage from mining containments and discriminating any such seepage from the natural bitumen background in groundwaters influenced by the Alberta McMurray formation. Improved sampling methods and quantitative analyses of two groups of monoaromatic acids were employed to analyze OSPW and bitumen-affected natural background groundwaters for source discrimination. Both groups of monoaromatic acids showed significant enrichment in OSPW, while ratios of O /O containing heteroatomic ion classes of acid extractable organics (AEOs) did not exhibit diagnostic differences. Evaluating the monoaromatic acids to track a known plume of OSPW-affected groundwater confirmed their diagnostic abilities. A secondary objective was to assess anthropogenically derived artificial sweeteners and per- and polyfluoroalkyl substances (PFAS) as potential tracers for OSPW. Despite the discovery of acesulfame and PFAS in most OSPW samples, trace levels in groundwaters influenced by general anthropogenic activities preclude them as individual robust tracers. However, their inclusion with the other metrics employed in this study served to augment the tiered, weight of evidence methodology developed. This methodology was then used to confirm earlier findings of OSPW migrations into groundwater reaching the Athabasca River system adjacent to the reclaimed pond at Tar Island Dyke

Preparative isolation, fractionation and chemical characterization of dissolved organics from natural and industrially derived bitumen-influenced groundwaters from the Athabasca River watershed

Recent analytical advances have provided evidence that groundwater affected by oil sands process-affected water (OSPW) is reaching the Athabasca River at one location. To understand and discriminate the toxicological risks posed by OSPW-influenced groundwater relative to groundwaters associated with natural oil sands deposits, these highly complex mixtures of soluble organics were subjected to toxicological characterization through effects directed analysis. A recently-developed preparative fractionation methodology was applied to bitumen-influenced groundwaters and successfully isolated dissolved organics from both industrial and natural sources into three chemically distinct fractions (F1, F2, F3), enabling multiple toxicological assessments. Analytical techniques included electrospray ionization high resolution mass spectrometry (ESI-HRMS), liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF/MS), gas chromatography mass spectrometry (GC–MS), and synchronous fluorescence spectroscopy (SFS) methods, which did not reveal obvious differences between sources. Comparisons between fractions within each source consistently demonstrated that F3 contained compounds with greater polarity than F2, which in turn was more polar than F1. The abundance of O2 species was confined to F1, including naphthenic acids often cited for being the primary toxicants within bitumen-influenced waters. This result is consistent with earlier work on aged OSPW, as well as with other extraction methods, suggesting that additional factors other than molecular weight and the presence of acid functionalities play a prominent role in defining compound polarities and toxicities within complex bitumen-derived organic mixtures. The similarities in organic abundances, chemical speciation, aromaticity, and double bond equivalents, concomitant with inorganic mixture similarities, demonstrate the resemblances of bitumen-influenced groundwaters regardless of the source, and reinforce the need for more advanced targeted analyses for source differentiation.This work was funded under the Oil Sands Monitoring Program, and is a contribution to the Program, but does not necessarily reflect the position of the Program. Internal resources from Environment and Climate Change Canada were also used to fund this research

An added dimension : GC atmospheric pressure chemical ionization FTICR MS and the Athabasca oil sands

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

Data visualization for the characterization of naphthenic acids within petroleum samples

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 welt 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+O-z(x), 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

Salting-out effects on the characterization of naphthenic acids from Athabasca oil sands using electrospray ionization

There is growing interest in the mass spectrometric characterization of oil sands acids present in natural waters and contaminated soils. This interest stems from efforts to isolate the principal toxic components of oil sands acid extractable organics in aquatic environment. Salting-out effects are demonstrated for nanospray ionization mass spectra of Athabasca oil sands acid extractable organics (naphthenic acids), using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The differences in spectra obtained for the sodium naphthenates in dichloromethane/acetonitrile cosolvents compared to spectra obtained in the absence of saturated sodium chloride salts, are used here as a surrogate to indicate the more bioavailable or toxic components in natural waters. Whereas, monocarboxylic compounds (CnH2n+ZO2) were prevalent in the Z =-4, -6, and -12 (2, 3 and 6-ring naphthenic acids respectively) family in the carbon number range of 13 to 19 in the dichloromethane/acetonitrile cosolvent systems, salting-out effects resulted in a general enhancement of Z =-4 species, relative to others. Likewise, the shift in relative intensities of species containing O1, O3, O4, O2S and O3S was dramatic for systems with and without saturated salts present. The O4 and O3S species for example, were prevalent in the dichloromethane/acetonitrile cosolvent but were non-detected in the presence of saturated salts. Interactions of oil sands acids with salts are expected to occur in oil sands processed waters and natural saline waters. As evident by the distribution of species observed, salting-out effects will play a major role in limiting the bioavailability of oil sands acids in aquatic systems

An Added Dimension: GC Atmospheric Pressure Chemical Ionization FTICR MS and the Athabasca Oil Sands

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 O_<i>x</i> and O_<i>x</i>S compound classes predominated, with O_<i>x</i>S 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