Limits of identification using VUV spectroscopy applied to C8H18 isomers isolated by GC×GC

David C Bell; John Feldhausen; Aaron J Spieles; Randall C Boehm; Joshua S Heyne

doi:10.1016/j.talanta.2023.124451

Limits of identification using VUV spectroscopy applied to C8H18 isomers isolated by GC×GC

Talanta. 2023 Jun 1:258:124451. doi: 10.1016/j.talanta.2023.124451. Epub 2023 Mar 13.

Authors

David C Bell¹, John Feldhausen², Aaron J Spieles³, Randall C Boehm², Joshua S Heyne⁴

Affiliations

¹ Bioproduct Sciences and Engineering Laboratory, School of Engineering and Applied Science, Washington State University, Richland, WA, 99354, USA. Electronic address: David.C.Bell@wsu.edu.
² Bioproduct Sciences and Engineering Laboratory, School of Engineering and Applied Science, Washington State University, Richland, WA, 99354, USA.
³ Department of Mechanical and Aerospace Engineering, University of Dayton, 300 College Park, Dayton, OH, 45469, USA.
⁴ Bioproduct Sciences and Engineering Laboratory, School of Engineering and Applied Science, Washington State University, Richland, WA, 99354, USA; Energy Processes and Materials Division, Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.

PMID: 36931058
DOI: 10.1016/j.talanta.2023.124451

Abstract

The vacuum ultraviolet detector for gas chromatography can be used to identify structural differences between isomers with similar chromatographic elution times, which adds detail to characterization, valuable for prescreening of sustainable aviation fuel candidates. Although this capability has been introduced elsewhere, vacuum ultraviolet spectroscopy for saturated hydrocarbons has been examined minimally, as the similarities between their spectra are much less significant than their aromatic counterparts. The fidelity with which structural differences can be identified has been unclear. In this work, all possible structural isomers of C₈H₁₈ are measured and determined to have unambiguously unique vacuum ultraviolet spectra. Using a statistically based residual comparison approach, the concentration limits at which the spectral differences are interpretable are tested in both a controlled study and a real fuel application. The concentration limit at which the spectral differences between C₈H₁₈ isomers are unambiguous is below 0.40% by mass and less than 0.20% with human discretion in our experimental configuration.

Keywords: GC×GC; Isomer identification; Sustainable aviation fuel; Vacuum ultraviolet spectroscopy.