The comprehensive chemical characterization of crude oil is important for the evaluation of the transformation and fate of components in the environment. Molecular-level speciation of naphthenic acid fraction compounds (NAFCs) was investigated in a mesoscale spill tank using both negative-ion electrospray ionization (ESI) Orbitrap mass spectrometry (MS) and positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI-FT-ICR-MS). Both ionization techniques are coupled to high-resolution mass spectrometric detectors (ESI: Orbitrap MS; APPI: FT-ICR-MS at 9.4 T), enabling insight into the behavior and fate of petrogenic compounds during a simulated freshwater crude oil spill. Negative-ion ESI Orbitrap-MS reveals that oxygen-containing (O_x) classes are detected early in the spill, whereby species with more oxygen per molecule evolve later in the simulated spill. The O₂-containing species gradually decreased in relative abundance, while O₃ and O₄ species increased in relative abundance throughout the simulated spill, which could correspond to a relative degree of oxygen incorporation. Nonpolar speciation by positive-ion APPI 9.4 T FT-ICR-MS allowed for the identification of water-soluble nonpolar and less polar acidic species. Molecular-level graphical representation of elemental compositions derived from simulated spill water-soluble and oil-soluble species suggest that biological activity is the primary degradation mechanism and that biodegradation was the dominant mechanism based on the negative-ion ESI Orbitrap-MS results.

中文翻译：

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通过 Orbitrap 和傅里叶变换离子回旋共振质谱法评估模拟淡水-石油泄漏中极性和非极性石油成分的风化

原油的综合化学表征对于评估环境中成分的转化和归宿具有重要意义。使用负离子电喷雾电离 (ESI) Orbitrap 质谱 (MS) 和正离子大气压光电离傅里叶变换离子回旋共振质谱 (MS) 在中尺度溢出罐中研究了环烷酸馏分化合物 (NAFC) 的分子水平形态形成。 APPI-FT-ICR-MS）。两种电离技术均与高分辨率质谱检测器（ESI：Orbitrap MS；APPI：9.4 T 的 FT-ICR-MS）相结合，从而能够深入了解模拟淡水原油泄漏过程中成岩化合物的行为和命运。负离子 ESI Orbitrap-MS 揭示了在泄漏早期检测到的含氧 (O _x ) 类物质，其中每个分子含有更多氧气的物种在模拟泄漏后期演化。在整个模拟泄漏过程中，含O ₂物质的相对丰度逐渐下降，而O ₃和O ₄物质的相对丰度增加，这可能与氧结合的相对程度相对应。通过正离子 APPI 9.4 T FT-ICR-MS 进行非极性形态分析，可以鉴定水溶性非极性和极性较小的酸性物质。来自模拟泄漏水溶性和油溶性物质的元素组成的分子水平图形表示表明，生物活性是主要降解机制，并且基于负离子 ESI Orbitrap-MS 结果，生物降解是主要机制。