Orbitrap Mass Spectrometry: A Proposal for Routine Analysis of Nonvolatile Components of Petroleum

• Published in: Energy & fuels 2011-07, Vol.25 (7), p.3077-3082
• Main Authors: Pomerantz, Andrew E, Mullins, Oliver C, Paul, Gary, Ruzicka, Josef, Sanders, Mark
• Format: Article
• Language: English
• Subjects: Fossil Fuels
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef200359n

High-resolution mass spectrometry can provide a detailed fingerprint of the composition of the nonvolatile fraction of petroleum. That analysis is typically performed using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, which offers greater mass resolution than any other mass analyzer. While high resolution is desirable for complex mixtures, such as petroleum, the high costs associated with FT-ICR limit its use to a small number of research laboratories, limiting the impact of the measurement relative to more accessible techniques. Here, we explore whether there is a role for other high-resolution mass analyzers to complement FT-ICR. One such high-resolution mass analyzer is the LTQ Orbitrap XL, which presents significantly lower costs relative to typical FT-ICR instruments. The Orbitrap mass analyzer provides mass resolution inferior to the modern FT-ICR instrument but still sufficient to assign molecular formulas to individual components present in mixtures, especially those components present in relatively high abundance. Indeed, the resolution of the LTQ Orbitrap XL is comparable to that obtained by FT-ICR instruments 1 decade ago, at which time FT-ICR was being used successfully to fingerprint petroleum. Here, we demonstrate successful application of the Orbitrap to resolve and identify >1000 of the more abundant molecular formulas in the negative ion electrospray ionization mass spectrum of a petroleum sample. These results are compared to the 9.4 T FT-ICR analysis of the same sample (published previously; Pomerantz A. E. ; Ventura G. T. ; McKenna A. M. ; Cañas J. ; Auman J. ; Koerner K. ; Curry D. ; Nelson R. K. ; Reddy C. M. ; Rodgers R. P. ; Marshall A. G. ; Peters K. E. ; Mullins O. C. Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity. Org. Geochem. 2010, 41, 812–821 ), and in this analysis, both the compositional fingerprints and conclusions derived from those fingerprints are essentially the same for the FT-ICR and Orbitrap data. Setting up and operating a LTQ Orbitrap XL mass spectrometer presents significantly lower initial and continuing costs compared to setting up and operating a 9.4 T FT-ICR, and this difference may make the Orbitrap accessible to laboratories for which FT-ICR is cost-prohibitive. Although several valuable high-resolution mass spectrometric analyses require the extremely high resolution of FT-ICR, we propose Orbitrap mass spectrometry as a method for rout