The comparison of naturally weathered oil and artificially photo-degraded oil at the molecular level by a combination of SARA fractionation and FT-ICR MS.
Two sets of oil samples, one obtained from different weathering stages of the M/V Hebei Spirit oil spill site and the other prepared by an in vitro photo-degradation experiment, were analyzed and compared at the molecular level by atmospheric pressure photo-ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). For a more detailed comparison at the molecular level, the oil samples were separated into saturate, aromatic, resin, and asphaltene (SARA) fractions before MS analysis. Gravimetric analysis of the SARA fractions revealed a decreased weight percentage of the aromatic fraction and an increased resin fraction in both sets of samples. Molecular-level investigations of the SARA fractions showed a significant reduction in the S1 class in the saturate fraction and increase of S1O1 class compounds with high DBE values in resin fraction. Levels of N1 and N1O1 class compounds resulting in protonated ions (presumably basic nitrogen compounds) increased after degradation compared to compounds generating molecular ions (presumably non-basic nitrogen compounds). This study revealed changes occurring in heteroatom polar species of crude oils such as sulfur and nitrogen containing compounds that have not been easily detected with conventional GC based techniques.
Kyungpook National University, Department of Chemistry, Daegu 702-701, Republic of Korea.
Ananna
A
Islam
Yunju
Y
Cho
Un Hyuk
UH
Yim
Won Joon
WJ
Shim
Young Hwan
YH
Kim
Sunghwan
S
Kim
D002244:Carbon / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005583:Fourier Analysis; D005648:Fuel Oils / Q000032:analysis*; D007477:Ions; D008027:Light; D013058:Mass Spectrometry; D009584:Nitrogen / Q000737:chemistry; D010578:Petroleum / Q000032:analysis*; D055668:Photochemical Processes; D010782:Photolysis; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared; D013455:Sulfur / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis
D005648:Fuel Oils; D007477:Ions; D010578:Petroleum; D011522:Protons; D014874:Water Pollutants, Chemical; D013455:Sulfur; D002244:Carbon; D009584:Nitrogen
Double bond equivalent; High resolution mass spectrometry; Oil spill; Petroleum; Photo-degradation