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.

No abstract

No abstract

No 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.