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

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• 作者：Ananna Islam ; Yunju Cho ; Un Hyuk Yim ; Won Joon Shim ; Young Hwan Kim ; Sunghwan Kim
• 关键词：Oil spill ; Photo-degradation ; High resolution mass spectrometry ; Double bond equivalent ; Petroleum
• 刊名：Journal of Hazardous Materials
• 出版年：15 December, 2013
• 年：2013
• 卷：263
• 期：part_P2
• 页码：404-411
• 全文大小：2350 K

文摘

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.