Characterization of Deasphalted Crude Oils Using Gas Chromatography–Atmospheric Pressure Laser Ionization–Trapped Ion Mobility Spectrometry–Time-of-Flight Mass Spectrometry

Abstract

In the present work, a novel workflow based on complementary gas-phase separations is applied to the characterization of deasphalted light (Macondo and Calvert), medium (Duri), and heavy (San Ardo) crude oils. The coupling of gas chromatography (GC), atmospheric pressure laser ionization (APLI), and trapped ion mobility spectrometry−mass spectrometry (TIMS−MS) resulted in the effective separation and candidate assignment of polycyclic aromatic hydrocarbons (PAHs) and similar compounds. The analytical power of GC− APLI−TIMS−TOF MS is based on the separation of the isomeric content using the GC and TIMS (R = 50−90 with S r = 0.18 V/ms) gas-phase separations, followed by the high mass resolution and mass accuracy (<2 ppm) of the TOF MS analyzer. Previously reported PAH-like known compounds (130 compounds) uniquely assigned on the basis of their retention time (RT), collisional cross section (CCS), and mass-to-charge ratio (m/z) showed signature patterns and distinctive diagnostic ratios representative of the thermal maturity, lithology, and microbial contribution to each oil formation. The unsupervised T-Rex 4D analysis of GC−APLI−TIMS−TOF MS generated for the first time an exhaustive list of PAHs and similar unknown components (∼8500), with each component characterized by a RT, CCS, m/z value, and chemical formula and peak areas for each replica analysis (i.e., 12 total, 3× per crude oil). The inspection of the PAHs and similar unknown compounds provided a list of unique identifiers for each crude oil (2−4% of the assigned compounds) as well as molecular components common to all crude oils (∼50% of the assigned compounds). The analytical power of GC−APLI−TIMS−TOF MS is illustrated using unsupervised principal component analysis (PCA), where the four oils can be easily separated in two principal components that account for 70% of the total variance.

Chemoselective derivatisation and ultrahigh resolution mass spectrometry for the determination of hydroxyl functional groups within complex bio-oils

“…The quantication of the hydroxyl group in individual moieties of a complex mixture will require the separation of each reactive chemical within the biooil, calibration curves, authentic standards covering the mass range of detection (4000-5000, elemental compositions were detected), and measuring ionisation response against concentration. Individual isomers are, however, not discriminated by direct infusion mass spectrometry and thus hyphenated techniques such as gas chromatography, GC × GC, and liquid chromatography, or alternatively, ion mobility [50][51][52] can be used to deliver a more detailed insight of the hydroxyl group prole. Future work will focus on the use of chemical derivatisations combined with hyphenated mass spectrometry to allow the separation of isomeric compositions and overlapping reactant/ products elemental molecular compositions.…”

Virtual Special Issue of Recent Advances in Analysis of Fuels and Products by Advanced Mass Spectrometry

“…Analysis of fouling reaction products using Orbitrap Elite mass spectrometry and electron microscopy shows that a radical-induced mechanism plays a role for the decomposition of sulfur-containing compounds at an elevated temperature. Olanrewaju et al characterized deasphalted crude oils by use of gas chromatography–atmospheric pressure laser ionization–trapped ion mobility spectrometry–time-of-flight mass spectrometry. Observed compounds are effectively identified on the basis of the retention time, collisional cross section, m / z value, and chemical formula.…”

“…Analysis of fouling reaction products using Orbitrap Elite mass spectrometry and electron microscopy shows that a radical-induced mechanism plays a role for the decomposition of sulfur-containing compounds at an elevated temperature. Olanrewaju et al 8 13 report the combination of a high-pressure autoclave with online soft photoionization mass spectrometry and its application in catalytic hydrotreatment of a biomass model compound in liquid phase. The advantage of such online mass spectrometric methodology is highlighted, especially for process analysis of chemical reactions under harsh conditions.…”

The dependence of reduced mobility, ion-neutral collisional cross sections, and alpha values on reduced electric field strengths in ion mobility

“…While traditionally reserved for security applications, 1–7 ion mobility spectrometry (IMS) has been increasingly used over the past decade for a growing variety of applications. Examples of new(er) applications using IMS include proteomics, 8–10 metabolomics, 11–14 lipidomics, 15–18 petroleomics, 19,20 glycomics, 21,22 and characterizing PFAS substances 23,24 to name a few. IMS is appealing specifically because it is a gas-phase separation technique easily coupled between mass spectrometry and other chromatography devices which grants an additional degree of separation and identification for complex sample matrices.…”