Analysis of Selected Staling Aldehydes in Wort and Beer by GC-EI-MS/MS Using HS-SPME with On-Fiber Derivatization

Abstract

Quantification of staling aldehydes from wort and beer requires sensitive instrumental analysis. In the brewing industry, this is for the most part accomplished by gas chromatography-mass spectrometry (GC-MS) using headspace solid-phase microextraction (HS-SPME) and on-fiber derivatization (OFD) with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA). With respect to lipid oxidation products (e.g., (E)-2-nonenal) and minor Strecker aldehydes (e.g., methional), the sensitivity of GC-EI-MS might not be sufficient to ensure reliable quantification and long-term stability regarding method performance. To overcome these problems, an elaborate gas chromatography-electron impact-tandem mass spectrometry (GC-EI-MS/MS) methodology was implemented. GC-EI-MS/MS improved sensitivity and reduced matrix effects resulting from overlapping PFBHA-oximes (PFBOs). It enabled reliable quantification of 15 selected aldehydes in different matrices (wort, beer) across a wide concentration range (0.01 − 1000 µg/L). Extensive method validation and long-term stability testing proved excellent method performance. Lastly, direct comparison of GC-EI-MS/MS and GC-EI-MS revealed that the quantification of low abundant aldehydes via GC-EI-MS/MS is more reproducible and that lower limits of quantification were achieved.

Keywords:

• Beer aging
• mass spectrometry
• on-fiber derivatization
• SPME
• staling aldehydes

Additional information

Funding

This research received partial funding by the German Federal Ministry for Economic Affairs and Energy. Data presented herein is part of the project MF150164, the GC-MS/MS instrument is part of grant number 49IZ180038.