Identification of Water-Soluble Heavy Crude Oil Organic-Acids, Bases, and Neutrals by Electrospray Ionization and Field Desorption Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Abstract

We identify water-soluble (23 degrees C) crude oil NSO nonvolatile acidic, basic, and neutral crude oil hydrocarbons by negative-ion ESI and continuous flow FD FT-ICR MS at an average mass resolving power, m/deltam50% = 550,000. Of the 7000+ singly charged acidic species identified in South American crude oil, surprisingly, many are water-soluble, and much more so in pure water than in seawater. The truncated m/z distributions for water-soluble components exhibit preferential molecular weight, size, and heteroatom class influences on hydrocarbon solubility. Acidic water-soluble heteroatomic classes detected at >1% relative abundance include O, O2, O3, O4, OS, O2S, O3S, O4S, NO2, NO3, and NO4. Parent oil class abundance does not directly relate to abundance in the water-soluble fraction. Acidic oxygen-containing classes are most prevalent in the water-solubles, whereas acidic nitrogen-containing species are least soluble. In contrast to acidic nitrogen-containing heteroatomic classes, basic nitrogen classes are water-soluble. Water-soluble heteroatomic basic classes detected at >1% relative abundance include N, NO, NO2, NS, NS2, NOS, NO2S, N2, N2O, N2O2, OS, O2S, and O2S2.

Petroleomics: Chemistry of the underworld

“…Interestingly, the O 2 class (presumably carboxylic acids) are not aromatic because their DBE values are typically 4 or less (and the simplest aromatic carboxylic acid would have DBE ϭ 5). Plots of DBE vs. carbon number have proved especially useful in characterizing hydrotreatment in petroleum processing (22)(23)(24), vacuum gas oil distillation cuts (25), water-soluble acids and bases (26), saturates vs. aromatics (27), heat exchanger deposits (28), oil:water emulsion interfacial material (29-31), (lack of) matrix effects in saturates/aromatics/ resins/asphaltenes (SARA) (32) fractionation (33), naphthenic acids (1, 34, 35), sulfur-containing polycyclic aromatics (27,(36)(37)(38), distillates (39,40), and other applications discussed in this article.…”

Sunlight creates oxygenated species in water-soluble fractions of Deepwater horizon oil

“…The current study was carried out in controlled laboratory conditions so that direct observation of photochemical transformations of oil composition could be observed. Previous studies have targeted oil molecules that partition into water (water soluble organics, WSO) [22][23][24]. Stanford et al identified molecular formulas of water-soluble species present in South American and Medium Arabian crude oils by FT-ICR MS [24].…”

“…Previous studies have targeted oil molecules that partition into water (water soluble organics, WSO) [22][23][24]. Stanford et al identified molecular formulas of water-soluble species present in South American and Medium Arabian crude oils by FT-ICR MS [24]. Fathalla and Andersson observed formation of oxygenated products upon irradiation of polycyclic aromatic sulfur heterocycle oil fractions [25].…”

Direct Mass Spectroscopy Analysis and Comparison of Middle Eastern and Texas Crude Oils

“…While the determination of volatile and non-polar components has been achieved by gas chromatography/mass spectrometry (GC/MS), the identification of trace polar components in crude oil is performed using liquid chromatography/mass spectrometry (LC/MS) [8]. Mass spectrometric ionization techniques, namely, electron impact ionization (EI) [9], field ionization (FI) [10], and field desorption (FD) [11] are sufficient for analysis of volatile and semi volatile compounds in crude oil [8]. For the analysis of the compounds with higher boiling points, producing characteristic fragments, pyrolysis/mass spectrometry (Py/MS) or pyrolysis/gas chromatography/mass spectrometry (Py/GC/MS) needs to be considered [12].…”