Molecular profiling of naphthenic acids in technical mixtures and oil sands process‐affected water using polar reversed‐phase liquid chromatography–mass spectrometry

Abstract

In this work, a reversed-phase ultra-HPLC (UHPLC) ultrahigh resolution MS (UHRMS) method was evaluated for the comprehensive profiling of NAs containing two O atoms in each molecule (O2NAs; general formula C H O , where n is the number of carbon atoms and z represents hydrogen deficiency). Using a polar cyanopropyl-bonded phase column and negative-ion electrospray ionization mass spectrometric detection at 120,000 FWHM (m/z 400), 187 and 226 O2NA species were found in two naphthenic acid technical mixtures, and 424 and 198 species with molecular formulas corresponding to O2NAs were found in two oil sands process-affected water samples (one from a surface mining operation and the other from a steam-assisted gravity drainage operation), respectively. To our knowledge, these are the highest numbers of molecular compositions of O2NAs that have been profiled thus far in environmental samples. Assignments were based on accurate mass measurements (≤3 ppm) combined with rational molecular formula generation, correlation of chromatographic behavior of O2NA homologues with their elemental compositions, and confirmation with carboxyl group-specific chemical derivatization using 3-nitrophenylhydrazine. Application of this UHPLC-UHRMS method to the quantitation of O2NAs in the surface mining operation-derived water sample showed excellent linearity (R = 0.9999) with external calibration, a linear range of 256-fold in concentration, and quantitation accuracies of 64.9 and 69.4% at two "standard substance" spiking levels.

Characterization of Naphthenic Acids and Other Dissolved Organics in Natural Water from the Athabasca Oil Sands Region, Canada

“…This exceedingly high concentration is only 3–15× lower than NA concentrations in OSPW from active tailings ponds (6.34 to 29.0 mg/L) (Table S1). The NA concentrations in OSPW were generally consistent with Han at al.’s study . The NA concentration reported here for A5w-GW (2015) is similar to that obtained during the 2014 fall (2.20 mg/L) (Table S1).…”

“…'s study. 38 The NA concentration reported here for A5w-GW (2015) is similar to that obtained during the 2014 fall (2.20 mg/L) (Table S1). The low tritium concentration in A5w-GW also confirmed that natural inputs are the most likely source of these NAs.…”

Solvent and Flow Rate Effects on the Observed Compositional Profiles and the Relative Intensities of Radical and Protonated Species in Atmospheric Pressure Photoionization Mass Spectrometry

“…28 It was recently suggested that extraction of petroleum-related organic components can be maximized utilizing solutions predominantly comprising ethyl acetate (EA), rather than the more routinely used DCM. 6 Improved access to the compositional space may be afforded, 29,30 and the resulting profiles have been considered useful for statistical comparison to environmental samples. 31 To the best of our knowledge, the effect of these solvents on the observed profile has not yet been investigated with respect to the analysis of crude oil.…”

Acidic molecular fossils: origin, isolation and applications

“…Z is equal to 0 for saturated, acyclic acids and increases to 2 in monocyclic naphthenic acids, 4 in bicyclic naphthenic acids, 6 in tricyclic acids, and 8 in tetracyclic acids (Figure 27) (YANG et al, 2019). analysis (BATAINEH et al, 2006;DAMASCENO et al, 2014) in water and soil samples from areas associated with oil refineries (GREWER et al, 2010;HAN et al, 2016;BARROW, 2016;HINDLE et al, 2013;HUGHES et al, 2017;SHANG et al, 2013;KASPERSKI, 2010;YANG et al, 2019) or in crude oils (HEADLEY; PERU;…”