Elemental Composition Validation from Stored Waveform Inverse Fourier Transform (SWIFT) Isolation FT-ICR MS Isotopic Fine Structure
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Elemental composition assignment confidence in mass spectrometry is typically assessed by monoisotopic mass accuracy. For a given mass accuracy, resolution and detection of other isotopologues can further narrow the number of possible elemental compositions. However, such measurements require ultrahigh resolving power and high dynamic range, particularly for compounds containing low numbers of nitrogen and oxygen (both 15N and 18O occur at less than 0.4 % natural abundance). Here, we demonstrate validation of molecular formula assignment from isotopic fine structure, based on ultrahigh resolution broadband Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Dynamic range is enhanced by external quadrupole and internal stored waveform inverse Fourier transform (SWIFT) isolation to facilitate detection of low abundance heavy atom isotopologues.
Key wordsExcitation Dynamic range Mass spectrometry High resolution Isotopologue
The work was supported by the National Science Foundation (NSF) Division of Materials Research through DMR-11-57490, NSF CHE-10-49753, the BP/The Gulf of Mexico Research Initiative to the Deep-C Consortium, the State of Florida, and NSF grants OCE-1044939 and OCE-1057417. The authors thank Markus Huettel and Joel Kostka for the Pensacola Beach oil spill contaminant sample, and Jeremiah Purcell for the heavy crude oil (bitumen) sample. The authors also thank Joshua Savory, Nathan Kaiser, Amy McKenna, and Jacqueline Jarvis for helpful discussions. Special thanks to John Quinn and Dan McIntosh for design and fabrication of the custom instrument components.
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