Comprehensive Screening of Polycyclic Aromatic Hydrocarbons and Similar Compounds Using GC–APLI–TIMS–TOFMS/GC–EI–MS

Abstract

In the present work, a novel workflow based on complementary gas-phase separations for the identification of isomeric PAHs from complex mixtures is described. This is the first report on the coupling of gas chromatography (GC), atmospheric pressure laser ionization (APLI), and trapped ion mobility spectrometry–mass spectrometry (TIMS–MS) for the characterization of polycyclic aromatic hydrocarbons. Over a hundred known unknowns are uniquely identified based on the molecular ion retention indices I (5%), mobility (RSD < 0.6% and R = 50–90 with S r = 0.18 V/ms), mobility-based theoretical candidate assignment (<3%), accurate mass chemical formula assignment (<2 ppm), and electron impact fragmentation pattern and database search. The advantages of theoretical modeling of PAHs and similar compounds were evaluated using candidate structures ranked by retention indices and fragmentation pattern from GC–EI–MS data sets. Over 20 PAH isomeric and deuterated standards were utilized for the GC–APLI–TIMS–TOF MS workflow validation. Noteworthy is the analytical capability for untargeted screening of isomeric and isobaric compounds with additional characterization metrics not available in traditional GC–EI–MSn workflows.

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

“…All standards were diluted in hexane before use to a final concentration of 4 mg/L. Details on the preparation of deasphalted crude oil samples can be found elsewhere . Briefly, 50 mg of the crude oil was carefully weighed and mixed with 100 μL of the deuterated PAHs (Table S1 of the Supporting Information).…”

“…Previous studies have shown that atmospheric pressure laser ionization (APLI) is more suitable for accessing the PAH content in crude oils . With the coupling of GC–APLI, the characterization of PAH-like components using commercial MS analyzers was realized. , Recently, we described the advantages of complementary gas-phase separations for the identification of isomeric PAHs from complex mixtures using GC–APLI–TIMS–TOF MS; noteworthy is the analytical capability for untargeted screening of isomeric and isobaric compounds not available in traditional GC–EI–MS n workflows.…”

Nontargeted Screening Using Gas Chromatography–Atmospheric Pressure Ionization Mass Spectrometry: Recent Trends and Emerging Potential

“…They used an in-house database consisting of 800 CCS values to screen for drug-like compounds and pesticides [21]. Recently, Olanrewaju et al [95] have analyzed PAHs and related petroleum hydrocarbons in crude oil using a trapped ion mobility-mass spectrometer hyphenated with GC. In this study, the identification of isomeric PAHs and related unknown aromatic hydrocarbons was accomplished with the aid of CCS measurements.…”

Review on Evolved Gas Analysis Mass Spectrometry with Soft Photoionization for the Chemical Description of Petroleum, Petroleum-Derived Materials, and Alternative Feedstocks

“…In this context, Barrow et al first brought GC–APCI to high-resolution mass spectrometric detection for the characterization of oil sands, whereas Benigni et al showed the sensitivity of APLI toward polycyclic aromatic hydrocarbons in GC–APLI high-resolution mass spectrometry . Very recently, the Fernandez-Lima group expanded the analytical performance for hydrocarbon speciation by additional integration of ion mobility separation . Integration of fast ion mobility separation (∼milliseconds) creates new capabilities for untargeted screening of the isomeric and isobaric complexity.…”

“…34 Very recently, the Fernandez-Lima group expanded the analytical performance for hydrocarbon speciation by additional integration of ion mobility separation. 92 Integration of fast ion mobility separation (∼milliseconds) creates new capabilities for untargeted screening of the isomeric and isobaric complexity. In particular, the collision cross-section (CCS) information retrieved from ion mobility spectrometry adds an additional metric not accessible by classical fragmentation and tandem mass spectrometry.…”