Evaluations of Weathering of Polar and Nonpolar Petroleum Components in a Simulated Freshwater-Oil Spill by Orbitrap and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

The comprehensive chemical characterization of crude oil is important for the evaluation of the transformation and fate of components in the environment. Molecular-level speciation of naphthenic acid fraction compounds (NAFCs) was investigated in a mesoscale spill tank using both negative-ion electrospray ionization (ESI) Orbitrap mass spectrometry (MS) and positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI-FT-ICR-MS). Both ionization techniques are coupled to high-resolution mass spectrometric detectors (ESI: Orbitrap MS; APPI: FT-ICR-MS at 9.4 T), enabling insight into the behavior and fate of petrogenic compounds during a simulated freshwater crude oil spill. Negative-ion ESI Orbitrap-MS reveals that oxygen-containing (Ox) classes are detected early in the spill, whereby species with more oxygen per molecule evolve later in the simulated spill. The O2-containing species gradually decreased in relative abundance, while O3 and O4 species increased in relative abundance throughout the simulated spill, which could correspond to a relative degree of oxygen incorporation. Nonpolar speciation by positive-ion APPI 9.4 T FT-ICR-MS allowed for the identification of water-soluble nonpolar and less polar acidic species. Molecular-level graphical representation of elemental compositions derived from simulated spill water-soluble and oil-soluble species suggest that biological activity is the primary degradation mechanism and that biodegradation was the dominant mechanism based on the negative-ion ESI Orbitrap-MS results.

Advances in mass spectrometry for molecular characterization of oil sands naphthenic acids and process chemicals in wetlands

Advances in mass spectrometry in the authors’ and key collaborators’ research are reviewed for analysis of oil sands naphthenic acids fraction compounds (NAFCs) and industrial process chemicals, sulfolane and alkanolamines, in wetlands. Focus is given to developments of analyses of NAFCs in constructed wetland treatment systems and natural wetlands in the Athabasca oil sands region, Alberta, Canada. The analytical developments are applied to show the utility of wetlands to sequester and oxidize oil sands naphthenic acids. The advancements in molecular characterization led to the first application of high-resolution mass spectrometry (Fourier transform ion-cyclotron resonance and Orbitrap mass spectrometry) for elucidation of toxic mono- and di-carboxylic NAFCs in oil sands environmental samples. Key findings reveal that oil sands NAFCs are not limited to saturated structures but contain a diverse range of components, many of which contain S, N, heteroatomic species and aromatic species. Other developments of mass spectrometry methods for industrial process chemicals show for the first time that the completely water-miscible chemical, sulfolane, translocate to upper portions of cattails at natural wetland sites in the Canadian environment. Likewise, wetland-plant mediated changes of complex mixtures of alkanolamines were revealed based on the coupling of ion chromatography mass spectrometry and ultrahigh resolution mass spectrometry. The advances in mass spectrometry are of particular benefit to Canada, for development of soil and water quality guidelines for oil sands NAFCs and process chemicals. In turn, the water quality guidelines serve to protect Canadian aquatic environments.