Molecular-Level Characterization of Oil-Soluble Ketone/Aldehyde Photo-Oxidation Products by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Reveals Similarity between Microcosm and Field Samples

Molecular-Level Characterization of Oil-Soluble Ketone/Aldehyde Photo-Oxidation Products by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Reveals Similarity between Microcosm and Field Samples

Crude oil

Extraction

Phase separation

Petroleum industry

Weathering

Biodegradation

Mass spectrometry

Oxidation

Oil spills

Ketones

Solar radiation

Cyclotrons

Electron cyclotron resonance

Fourier transforms

We present a solid-phase extraction method followed by derivatization with a charged tag to characterize ketone/aldehyde-containing functionalities (proposed photo-oxidation transformation products) in weathered petroleum by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). A photo-oxidation-only microcosm mimics solar irradiation of crude oil in the environment after an oil spill. A biodegradation-only microcosm enables independent determination as to which of the two weathering processes contributes to the formation of oil-soluble ketone/aldehyde species. Results confirm that photo-oxidation produces ketones/aldehydes in crude oil when exposed to solar radiation in laboratory experiments, whereas biodegraded oil samples do not produce ketone/aldehyde compounds. Field samples collected after different time periods and locations after the Deepwater Horizon oil spill are also shown to contain ketones/aldehydes, and comparison of field and photo-oxidation-only microcosm transformation products reveal remarkable similarity. These results indicate that the photo-oxidation microcosm comprehensively represents ketone/aldehyde-formation products in the field, whereas the biodegradation microcosm does not. Solid-phase extraction coupled with derivatization leads to selective identification of ketone/aldehyde species by MS. Although improved dynamic range and slightly reduced mass spectral complexity is achieved by separation/derivatization, comprehensive molecular characterization still requires mass resolving power and mass accuracy provided by FT-ICR MS. 2019 American Chemical Society.

6887-6894

53

Environmental Science and Technology

2019

Niles, Sydney F.

Chacon-Patino, Martha L.

Chen, Huan

McKenna, Amy M.

Blakney, Greg T.

Rodgers, Ryan P.

Marshall, Alan G.

journalArticle

0013936X

10.1021/acs.est.9b00908