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Targeted Petroleomics: Analytical Investigation of Macondo Well Oil Oxidation Products from Pensacola Beach
journal contribution
posted on 2015-12-17, 02:43 authored by Brian
M. Ruddy, Markus Huettel, Joel E. Kostka, Vladislav V. Lobodin, Benjamin J. Bythell, Amy M. McKenna, Christoph Aeppli, Christopher M. Reddy, Robert K. Nelson, Alan
G. Marshall, Ryan P. RodgersOf the estimated 5 million barrels
of crude oil released into the
Gulf of Mexico from the Deepwater Horizon oil spill, a fraction washed
ashore onto sandy beaches from Louisiana to the Florida panhandle.
Here, we compare the detailed molecular analysis of hydrocarbons in
oiled sands from Pensacola Beach to the Macondo wellhead oil (MWO)
by electrospray (ESI) and atmospheric pressure photoionization (APPI)
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR
MS) to identify major environmental transformation products of polar,
high molecular weight (C>25) “heavy ends”
(high-boiling species) inaccessible by gas chromatography. The petrogenic
material isolated from the Pensacola Beach sand displays greater than
2-fold higher molecular complexity than the MWO constituents, most
notably in oxygenated species absent in the parent MWO. Surprisingly,
the diverse oxygenated hydrocarbons in the Pensacola Beach sediment
extracts were dominant in all ionization modes investigated, (±)
ESI and (±) APPI. Thus, the molecular-level information highlighted
oxygenated species for subsequent “targeted” analyses.
First, time-of-flight mass spectrometry analysis of model compounds
attributes the unusually large oxygen signal magnitude from positive
electrospray to ketone transformation products (O1–O8 classes). Next, negative electrospray mass spectrometry reveals
carboxylic acid transformation products. Two-dimensional gas chromatography
with mass spectrometry analysis of anion-exchange chromatographic
fractions unequivocally verifies the presence of abundant alkyl ketone
fragments in sand extracts, and FT-ICR MS analysis reveals the distribution
of high-boiling ketone, carboxylic, and higher numbered (3+) oxygen-containing
transformation products too polar to be analyzed by gas chromatography.
The results expand compositional coverage of oxygen-containing functionalities
beyond the classic naphthenic acid type species to complex/mixed ketone,
hydroxyl, and carboxylic acid classes of molecules that have been
recently identified in produced water, emulsions, and petroleum production
deposits.
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model compounds attributeselectrospray mass spectrometryion cyclotron resonance mass spectrometrynaphthenic acid type speciespetroleum production depositsmass spectrometry analysisMWOhydrocarbonPensacola Beach sediment extractsPensacola Beach sand displaysOil Oxidation Productscarboxylic acid classescarboxylic acid transformation productsketone transformation productsalkyl ketone fragmentsDeepwater Horizon oil spillfractionAPPIoxygenated speciesMacondo wellhead oilgas chromatographyMSESIoxygen signal magnitude
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