Structural assignments of sulfur-containing compounds in crude oil using Ion Mobility Spectrometry-Mass Spectrometry (IMS-MS)

Through proof-of-concept experiments, a preliminary structural characterization of isomeric and isobaric sulfur-containing compounds in petroleum is presented. Silver attachment to sulfur atom has been used for ionization enhancement of these compounds, which are less accessible by positive-ion electrospray ionization mass spectrometry (ESI-MS). Here, ion mobility spectrometry (IMS) is combined with the enhanced ionization approach and MS to characterize sulfur compounds in crude oil. The silver isotopes, being of nearly equal abundance and having a similar effect upon ion mobilities, provide a fingerprint for assignments of sulfur-containing ions in two-dimensional (2D) plots of mass-to-charge (m/z) vs drift time (tD). Fourier transform ion cyclotron resonance (FT-ICR) MS has been employed for the determination of molecular formulas for these ions. Collision-induced dissociation (CID) data are utilized to complement collision cross section (CCS) comparisons for candidate structures obtained from high mas...