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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)
journal contribution
posted on 2016-01-06, 16:49 authored by Paolo Benigni, J. Daniel DeBord, Christopher
J. Thompson, Piero Gardinali, Francisco Fernandez-LimaThousands
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.