Published:Journal of Chromatographic Science,
ISSN 0021-9665 Volume
46, Number 4, April 2008, pp. 339-344
Photodegradation of Crude Oil: Liquid Injection
and Headspace Solid-Phase Microextraction for Crude Oil Analysis
by Gas Chromatography with Mass Spectrometer Detector
Maurizio D’Auria, Rocco Racioppi, and
Vincenzina Velluzzi
Dipartimento di Chimica, Università degli Studi della
Basilicata, Via N. Sauro 85, 85100 Potenza, Italy
The fate of crude oil under irradiation is studied.
After UV irradiation, the fraction present in the highest percentage
shifts from the C8–C9 fractions to C13, using gas chromatography–mass
spectrometry (GC–MS) analysis in solution. An increase
of the relative amount of the C13–C25 fraction is observed,
while a decrease in the relative amount of the C7–C12 fractions
is present. In headspace solid-phase microextraction (HS–SPME)
analysis, the C8–C10 fractions represent 53% of all the
compounds detected. A decrease in the relative amount of the
C8–C10 fractions is observed, while C11–C15 fractions
increase. The irradiation of crude oil with a solar simulator
gives a mixture the analysis of which using GC–MS in solution
furnishes the same type of results: the relative amounts of linear
alkanes and aromatic compounds increase, while a sharp decrease
in the relative amounts of branched and cyclic alkanes is observed.
In the SPME analysis, a decreased relative amount of branched
alkanes and alkenes, and an increase in the relative amounts
of cyclic alkanes and aromatic compounds are observed. Analysis
of the distribution of the compounds in all the types of compound
shows that a dynamic equilibrium between different compounds
and different types of compounds is present. To confirm the presence
of a dynamic equilibrium, the irradiation of methylcyclohexane
in the presence of 2-methylnaphthalene shows the presence in
the reaction mixture of a small amount of tetradecane.
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