title: [Pre-print] Direct mass spectrometric analysis of naphthenic acids and polycyclic aromatic hydrocarbons in waters impacted by diluted bitumen and conventional crude oil
Creators: name: Monaghan, Joseph
name: Richards, Larissa C.
name: Vandergrift, Gregory W.
name: Hounjet, Lindsay J.
name: Stoyanov, Stanislav R.
name: Gill, Chris G.
name: Krogh, Erik T.
Publisher: name: Elsevier
Year: 2021
Subjects: subject: Naphthenic acids
subject: Environmental monitoring
subject: Mass spectrometry
subject: Polycyclic aromatic hydrocarbons
subject: Water--Pollution--Toxicology
subject: Oil spills

description: This document is a pre-copyedited, author-provided manuscript version of a published work that after revisions following peer review and technical editing by the publisher appeared in final form as: Monaghan, J., Richards, L.C., Vandergrift, G.W., Hounjet, L.J., Stoyanov, S.R., Gill, C.G., &amp; Krogh, E.T. (2021). Direct mass spectrometric analysis of naphthenic acids and polycyclic aromatic hydrocarbons in waters impacted by diluted bitumen and conventional crude oil. Science of the Total Environment, 765, 1-10. To access the final edited and published work see: http://doi.org/10.1016/j.scitotenv.2020.144206
description: The accidental release of hydrocarbons has well-documented, deleterious impacts on the hydrosphere. There are several classes of toxic petroleum derived compounds, such as naphthenic acids (NAs) and polycyclic aromatic hydrocarbons (PAHs), which may present a contamination hazard in the event of an oil spill. We examine the aqueous-phase concentrations of these trace contaminants using a direct sampling, on-line, rapid screening technique known as condensed-phase membrane introduction mass spectrometry (CP-MIMS). Water samples having a range of pH and salinity were equilibrated with either diluted bitumen (DB) or conventional crude (CC) oil. CP-MIMS is employed to directly measure concentrations and isomer class profiles of classical NAs in the aqueous phase using electrospray ionization in negative-ion mode as [M-H]–. Aqueous PAH concentrations are monitored using CP-MIMS coupled to liquid electron ionization (LEI) source in positive-ion mode using selected ion monitoring (SIM) of the molecular ion (M+•). Aqueous NA concentrations are observed to be highly pH-dependent, and are an order of magnitude greater in water samples contaminated with DB compared to CC. Conversely, aqueous concentrations of naphthalene and alkyl-naphthalenes are found to be greater in water samples exposed to CC. Principal component analysis of data generated from CP-MIMS for the NA profile in the aqueous phase enables discrimination of DB and CC as contaminant sources. In addition, we describe the use of online membrane sampling for real-time, direct detection of NAs and PAHs in the same sample. These compound classes are distinguished by both their perm-selectivity behaviour at the membrane and the ionization mode at the instrument. The in-situ analysis of trace organics in water with a simple workflow described here lays the foundation for applications of direct mass spectrometry to rapid screening of large sample sets and monitoring of aqueous-phase contamination and remediation processes in real-time.