Comprehensive Compositional Analysis of Hydrotreated and Untreated Nitrogen-Concentrated Fractions from 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 (N 2 , S 3 , NS 2 , NOS, O 3 , OS 2 , and O 2 S) below detectability, N-, S-, O-, O 2 -, OS-, and NO-containing compounds survived hydrotreatment. Analysis of N-, S-, and 0-containing compounds and hydrocarbon compounds at the molecular level exposes compositional changes and reveals the effectiveness of the hydrotreating process.