Issue 12, 2020

Barium ion adduct mass spectrometry to identify carboxylic acid photoproducts from crude oil–water systems under solar irradiation

Abstract

Petroleum derived dissolved organic matter (DOMHC) samples were successfully cationized with barium, revealing many [M–H + Ba]+ peaks in both dark and simulated sunlight treatments. The DOMHC samples generated after light exposure exhibited a greater number of [M–H + Ba]+ peaks compared to the dark control. Multiple [M–H + Ba]+ peaks were investigated in the irradiated DOMHC using low resolution MS/MS in order to confirm the presence of diagnostic fragment ions, m/z 139, 155 and 196 in each treatment. Due to the high complexity of the bariated DOMHC mixture, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS/MS) was employed to obtain molecular level information for both irradiated and dark treatments. The irradiated DOMHC treatments had more bariated oxygenated species over a wide range of H/C and O/C when compared to the dark controls. Doubly bariated species were also observed in DOMHC, which provides evidence that photochemistry transforms DOMHC to even more complex mixtures with multiple oxygenations per molecule. This study provides evidence that barium adduct mass spectrometry can be successfully applied to DOMHC screening for the presence of COOHs, both in dark samples and solar irradiated samples. Furthermore, direct evidence and molecular composition of aqueous phase crude oil photoproducts is provided by this technique.

Graphical abstract: Barium ion adduct mass spectrometry to identify carboxylic acid photoproducts from crude oil–water systems under solar irradiation

Supplementary files

Article information

Article type
Communication
Submitted
11 Sept. 2020
Accepted
31 Okt. 2020
First published
02 Nov. 2020

Environ. Sci.: Processes Impacts, 2020,22, 2313-2321

Author version available

Barium ion adduct mass spectrometry to identify carboxylic acid photoproducts from crude oil–water systems under solar irradiation

P. Zito, D. F. Smith, X. Cao, R. Ghannam and M. A. Tarr, Environ. Sci.: Processes Impacts, 2020, 22, 2313 DOI: 10.1039/D0EM00390E

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