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Determination of Elemental Compositions by Gas Chromatography/time‐of‐flight Mass Spectrometry Using Chemical and Electron Ionization by Salvatore Abate; Yun Gyong Ahn; Tobias Kind; Tommaso R. I. Cataldi; Oliver Fiehn is a Chemistry article available to read on EtoBox.

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## Abstract Many metabolomic applications use gas chromatography/mass spectrometry (GC/MS) under standard 70 eV electron ionization (EI) parameters. However, the abundance of molecular ions is often extremely low, impeding the calculation of elemental compositions for the identification of unknown compounds. On changing the beam‐steering voltage of the ion source, the relative abundances of molecular ions at 70 eV EI were increased up to ten‐fold for alkanes, fatty acid methyl esters and trimethylsilylated metabolites, concomitant with 2‐fold absolute increases in ion intensities. We have compared the abundance, mass accuracy and isotope ratio accuracy of molecular species in EI with those in chemical ionization (CI) with methane as reagent gas under high‐mass tuning. Thirty‐three peaks of a diverse set of trimethylsilylated metabolites were analyzed in triplicate, resulting in 342 ion species ([M+H]^+^, [M–CH~3~]^+^ for CI and [M]^+**.**^, [M–CH~3~]^+**.**^ for EI). On average, CI yielded 8‐fold more intense molecular species than EI. Using internal recalibration, average mass errors of 1.8 ± 1.6 m__m/z__ units and isotope ratio errors of 2.3 ± 2.0% (A+1/A ratio) and 1.7 ± 1.8% (A

Who reads Determination of Elemental Compositions by Gas Chromatography/time‐of‐flight Mass Spectrometry Using Chemical and Electron Ionization?

Author

Salvatore Abate; Yun Gyong Ahn; Tobias Kind; Tommaso R. I. Cataldi; Oliver Fiehn

Publisher

John Wiley and Sons; Wiley (John Wiley & Sons); John Wiley & Sons Inc.; Wiley (ISSN 0951-4198)

Published

2010

Language

EN

Field

Chemistry (Physical Sciences)