Comprehensive compositional analysis of hydrotreated and untreated nitrogen-concentrated fractions syncrude oil by electron ionization, field desorption ionization, and electrospray ionization ultrahigh-resolution FT-ICR mass spectrometry

Untreated and hydrotreated nitrogen-concentrated distillation fractions (483-504 °C) from Syncrude oil have been analyzed by electron ionization, field desorption ionization, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The routinely attainable mass resolving power ≥ 300 000 at m/z 300 and sub-ppm mass accuracy allowed for resolution and elemental compositional assignment of various compound classes. Multiple closely spaced mass doublets (with mass differences <10 mDa) were detected. Although hydrotreatment reduced the relative abundances of several heteroatomic classes (N₂, S₃, NS₂, NOS, O₃, OS₂, and O₂S) below detectability, N-, S-, O-, O₂-, OS-, and NO-containing compounds survived hydrotreatment. Analysis of N-, S-, and O-containing compounds and hydrocarbon compounds at the molecular level exposes compositional changes and reveals the effectiveness of the hydrotreating process.