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Analysis of Molecular Isotopic Structures at High Precision and Accuracy by Orbitrap Mass Spectrometry

Eiler, John and Cesar, Jaime and Chimiak, Laura and Dallas, Brooke and Grice, Kliti and Griep-Raming, Jens and Juchelka, Dieter and Kitchen, Nami and Lloyd, Max and Makarov, Alexander and Robins, Richard and Schwieters, Johannes (2017) Analysis of Molecular Isotopic Structures at High Precision and Accuracy by Orbitrap Mass Spectrometry. International Journal of Mass Spectrometry, 422 . pp. 126-142. ISSN 1387-3806. doi:10.1016/j.ijms.2017.10.002.

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Several technologies are being developed to examine the intramolecular isotopic structures of molecules (i.e., site-specific and multiple substitution), but limitations in sample size and type or (for mass spectrometry) resolution have so far prevented the creation of a general technique. We have now demonstrated the capacity for precise and accurate study of molecular isotopic contents and structures by Fourier transform mass spectrometry, using instruments containing a Thermo Scientific™ Orbitrap™ mass analyzer, here the Thermo Scientific Q Exactive GC™ and Q Exactive HF™ instruments. Orbitrap mass analyzers achieve mass resolutions in the range ∼250,000–1 M (FWHM) in the mass range of greatest interest to studies of molecular isotopic structure, 50–200 amu. This allows for resolution of many nearly isobaric interferences for compounds containing H, C, N, O and/or S. In this paper we show that internal and external experimental reproducibilities of isotope ratio analyses using the Orbitrap analysis can conform to shot-noise limits down to levels of tenths of per mil (1SE), with similar accuracy when standardized to reference materials. Precision reaches ±0.015‰ for exceptionally long integrations. Such measurements do not call for modifications to the ion optics of the Q Exactive instruments, but do require specially designed sample introduction devices to permit sample/standard comparison and long integration times. The sensitivity of the Q Exactive instruments permit analysis of sub-nanomolar samples and quantification of multiply-substituted species. Site-specific capabilities arise from the fact that mass spectra of molecular analytes commonly contain diverse fragment ion species, each of which samples a specific sub-set of molecular sites.

Item Type:Article
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Dallas, Brooke0000-0002-1313-3270
Lloyd, Max0000-0001-9367-2698
Additional Information:© 2017 Elsevier B.V. Received 20 July 2017, Revised 3 October 2017, Accepted 3 October 2017, Available online 9 October 2017.
Record Number:CaltechAUTHORS:20171018-091904641
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Official Citation:John Eiler, Jaime Cesar, Laura Chimiak, Brooke Dallas, Kliti Grice, Jens Griep-Raming, Dieter Juchelka, Nami Kitchen, Max Lloyd, Alexander Makarov, Richard Robins, Johannes Schwieters, Analysis of molecular isotopic structures at high precision and accuracy by Orbitrap mass spectrometry, In International Journal of Mass Spectrometry, Volume 422, 2017, Pages 126-142, ISSN 1387-3806, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82450
Deposited By: Tony Diaz
Deposited On:18 Oct 2017 23:24
Last Modified:15 Nov 2021 19:50

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