Throwing Light on Petroleum: Simulated Exposure of Crude Oil to Sunlight and Characterization Using Atmospheric Pressure Photoionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Abstract

The change in profile of crude oil following a release into the environment is a topic of significant interest, and there is a need to develop analytical methodologies for understanding natural processes which affect related complex mixture profiles. One such process is the exposure to sunlight. In the following investigation, three oil samples were studied: one served as a control, a second was subjected to irradiation by an ultraviolet lamp, and a third sample was irradiated by a SoLux light source which closely models the solar emission profile. The usage of the SoLux light source represents a new method which enables a controlled experiment to mimic the effects of sunlight upon the sample. Atmospheric pressure photoionization was selected as the primary ionization method due to the ability to ionize a broad range of compounds, including low polarity components which could not be observed using electrospray ionization. During a test of sample preparation methods, the addition of a protic cosolvent to the sample solutions was shown to broaden the range of heteroatom-containing components observed. Following characterization, it was found that the polyaromatic hydrocarbons did not change in profile, while compounds containing a heteroatom exhibited a tendency to oxidize following photoirradiation. Sulfur-containing compounds with a low number of double bond equivalents were among the most reactive components of the complex mixture. The photooxidation of compounds in petroleum, following exposure to sunlight, is expected to have significance with regards to solubility and potential toxicity.

Differentiating Fragmentation Pathways of Cholesterol by Two-Dimensional Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…By the same reasoning, the peak at m/z 387 can be said to result largely from scintillation noise from the signal resulting from the MH + ion of cholesterol. Compounds such as C 21 Table 1 in the Supplementary Materials) also dissociate via water loss and thus show peaks in the neutral loss scan of 18 Da. This fragmentation pattern is similar to the ones reported by Rossmann et al [48], Lembcke et al [49], and Ronsein et al [50] for cholesterol oxidations products.…”

“…This study shows the first coupling of 2D FT-ICR MS with an atmospheric pressure photoionization (APPI) [18,19] source, which, as a continuous ion source for both polar and nonpolar compounds [20,21], is a natural expansion for 2D…”

Weathering of Oil Spilled in the Marine Environment

“…In the presence of water and oxygen, exposure of oil to sunlight results in extensive oxygenation across a wide range of oil molecule types through the formation of excited triplets, singlet oxygen, and hydroxyl radical (Ray and Tarr, 2014a,b,c). Griffiths et al (2014) exposed neat oil (a light-sour crude) to ultra violet radiation (254 nm) or to light from a SoLux bulb (surrogate for sunlight) in open watch glasses for up to 938 hours. After exposure to the SoLux lamp, the oil had lost much of its liquid character, and high-resolution mass spectrometry revealed oxygenation of the oil.…”

Beyond Naphthenic Acids: Environmental Screening of Water from Natural Sources and the Athabasca Oil Sands Industry Using Atmospheric Pressure Photoionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…Electrospray ionization (ESI) provides the ability to study the acidic [27,28] and basic [29] components of fossil fuels. Some of the desorption and ionization methods have included field ionization [30], atmospheric pressure chemical ionization (APCI) [31], atmospheric pressure photoionization (APPI) [32,33], and atmospheric pressure laser ionization (APLI) [34].…”

“…An alternate approach is to utilize APPI, which is less sensitive to matrix effects than ESI [12,39]. APPI offers the additional advantage to extend the analyses of environmental samples beyond naphthenic acids to include other toxicologically relevant compound classes, such as PAHs and sulfur-containing species that would not be observed by conventional ESI [15,32,33].…”