[Post-print] Direct analysis of naphthenic acids in constructed wetland samples by condensed phase membrane introduction mass spectrometry

• Published in: Science of The Total Environment
• Main Authors: Duncan, Kyle D., Richards, Larissa C., Monaghan, Joseph, Simair, Monique C., Ajaero, Chukwuemeka, Peru, Kerry M., Friesen, Vanessa, McMartin, Dena W., Headley, John V., Gill, Chris G., Krogh, Erik T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2020
• Subjects: Krogh; Carex aquatilis
• Online Access: https://doi.org/10.1016/j.scitotenv.2020.137063; https://doi.org/10.25316/IR-17652; https://viurrspace.ca/handle/10613/25890

This is an accepted manuscript version of an article published as: Duncan, K.D., Richards, L.C., Monaghan, J., Simair, M.C., Ajaero, C., Peru, K.M., Friesen, V., McMartin, D.W., Headley, J.V., Gill, C.G., & Krogh, E.T. (2020). Direct analysis of naphthenic acids in constructed wetland samples by condensed phase membrane introduction mass spectrometry. Science of the Total Environment, 716, 1-8. https://doi.org/10.1016/j.scitotenv.2020.137063 The application of direct mass spectrometry techniques to the analysis of complex samples has a number of advantages including reduced sample handling, higher sample throughput, in situ process monitoring, and the potential for adaptation to on-site analysis. We report the application of a semi-permeable capillary hollow fibre membrane probe (immersed directly into an aqueous sample) coupled to a triple quadrupole mass spectrometer by a continuously flowing methanol acceptor phase for the rapid analysis of naphthenic acids with unit mass resolution. The intensity of the naphthenic acid-associated peaks in the mass spectrum are normalized to an internal standard in the acceptor phase for quantitation and the relative abundance of the peaks in the mass spectrum are employed to monitor compositional changes in the naphthenic acid mixture using principle component analysis. We demonstrate the direct analysis of a synthetic oil sands process-affected water for classical naphthenic acids (CnH2n+zO2) as they are attenuated through constructed wetlands containing sedge (Carex aquatilis), cattail (Typha latifolia), or bulrush (Schoenoplectus acutus). Quantitative results for on-line membrane sampling compare favourably to those obtained by solid-phase extraction high-resolution mass spectrometry. Additionally, chemometric analysis of the mass spectra indicates a clear discrimination between naphthenic acid-influenced and natural background waters. Furthermore, the compositional changes within complex naphthenic acid mixtures track closely with the degree of attenuation. ...