21 Tesla FT-ICR Mass Spectrometer for Ultrahigh-Resolution Analysis of Complex Organic Mixtures

Abstract

We describe complex organic mixture analysis by 21 tesla (T) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Ultrahigh mass-resolving power (m/Δm_50% > 2 700 000 at m/z 400) and mass accuracy (80 ppb rms) enable resolution and confident identification of tens of thousands of unique elemental compositions. We demonstrate 2.2-fold higher mass-resolving power, 2.6-fold better mass measurement accuracy, and 1.3-fold more assigned molecular formulas compared to our custom-built, state-of-the-art 9.4 T FT-ICR mass spectrometer for petroleum and dissolved organic matter (DOM) analyses. Analysis of a heavy petroleum distillate exemplifies the need for ultrahigh-performance mass spectrometry (49 040 assigned molecular formulas for 21 T versus 29 012 for 9.4 T) and extends the identification of previously unresolved O_o, S_sO_o, and NO_o classes. Mass selective ion accumulation (20 Thompson isolation) of an asphalt volcano sample yields 462 resolved mass spectral peaks at m/z 677 and reveals previously unresolved C_cH_hN_nO_oS_s mass differences at high mass (m/z > 600). Similar performance gains are realized in the analysis of dissolved organic matter, where doubly charged O_o species are resolved from singly charged SO_o species, which requires a mass-resolving power greater than 1 400 000 (at m/z 600). This direct comparison reveals the continued need for higher mass-resolving power and better mass accuracy for comprehensive molecular characterization of the most complex organic mixtures.