Increasing Polyaromatic Hydrocarbon (PAH) Molecular Coverage during Fossil Oil Analysis by Combining Gas Chromatography and Atmospheric-Pressure Laser Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)

Abstract

Thousands of chemically distinct compounds are encountered in fossil oil samples that require rapid screening and accurate identification. In the present paper, we show for the first time, the advantages of gas chromatography (GC) separation in combination with atmospheric-pressure laser ionization (APLI) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for the screening of polyaromatic hydrocarbons (PAHs) in fossil oils. In particular, reference standards of organics in shale oil, petroleum crude oil, and heavy sweet crude oil were characterized by GC-APLI-FT-ICR MS and APLI-FT-ICR MS. Results showed that, while APLI increases the ionization efficiency of PAHs, when compared to other ionization sources, the complexity of the fossil oils reduces the probability of ionizing lower-concentration compounds during direct infusion. When gas chromatography precedes APLI-FT-ICR MS, an increase (more than 2-fold) in the ionization efficiency and an increase in the signal-to-noise ratio of lower-concentration fractions are observed, giving better molecular coverage in the m/z 100–450 range. That is, the use of GC prior to APLI-FT-ICR MS resulted in higher molecular coverage, higher sensitivity, and the ability to separate and characterize molecular isomers, while maintaining the ultrahigh resolution and mass accuracy of the FT-ICR MS separation.

High‐resolution GC/MS studies of a light crude oil fraction

“…The above mentioned problems can now be overcome with the coupling of a gas chromatograph to an ultra‐high resolving mass spectrometer. Recently, the combination of GC and APLI has been successfully used for the analysis of polyaromatic hydrocarbons (PAHs) in fossil oil samples . Features such as sensitivity, high mass accuracy and high resolution can now be combined to a powerful chromatographic separation, enabling a deeper understanding of the samples on a molecular level …”

“…Recently, the combination of GC and APLI has been successfully used for the analysis of polyaromatic hydrocarbons (PAHs) in fossil oil samples. 28 Features such as sensitivity, high mass accuracy and high resolution can now be combined to a powerful chromatographic separation, enabling a deeper understanding of the samples on a molecular level. 29 This work illustrates the analytical performance of the newly developed GC Orbitrap-based mass spectrometer.…”

Evaluation of coal‐related model compounds using tandem mass spectrometry

“…Using GC/MS, Czechowski et al reported the distributions of n ‐alkanes from two brown coals with chain lengths ranging from C 12 to C 35 . The analysis of multiple polyaromatic hydrocarbons in fossil oil using GC/Fourier transform ion cyclotron resonance MS resulted in a high sensitivity …”

“…23 The analysis of multiple polyaromatic hydrocarbons in fossil oil using GC/Fourier transform ion cyclotron resonance MS resulted in a high sensitivity. 24 With the development of MS techniques, tandem MS (MS/MS) has been applied to minimize signal interferences in complicated samples, which can improve the sensitivity and increase the qualitative ability in monitoring coal conversions. 25,26 Gas chromatography/ quadrupole time-of-flight MS (GC/Q-TOF MS) has proven to be an effective approach for understanding the molecular compositions of unknown complexes.…”

Analysis of Photoirradiated Water Accommodated Fractions of Crude Oils Using Tandem TIMS and FT-ICR MS

“…59, 60, 65–69 However, the biggest challenge in the coupling of liquid and gas chromatography is that it limits the FT-ICR MS analysis time, and thus the ability to better separate isobaric species, due to the slow acquisition rates needed for ultrahigh resolution mass acquisitions. 48, 65 Alternatively, other post-ionization, gas-phase separations have been proven to be a better match for FT-ICR MS analysis. 70–79 In particular, ion mobility spectrometry (IMS) presents many advantages for the analysis of complex mixtures, providing orthogonal separation to FT-ICR MS that is based on the tri-dimensional structure of the molecule.…”