Non-targeted Analysis of Metabolites in Mouse Feces by GC-TOFMS
Introduction
Metabolites produced by the gut microbiota are partially absorbed in the intestine, circulate systemically, and are known to influence a broad range of host physiological functions—including immune, neural, and metabolic pathways. Accordingly, comprehensive profiling of microbiota-derived metabolites has gained increasing attention as a key approach for elucidating disease mechanisms and assessing the impact of nutrition and pharmaceuticals.
Gas chromatography-mass spectrometry (GC-MS) is widely used for qualitative analysis of such metabolites due to the breadth of available databases (e.g., the NIST database), ease of operation, and high reproducibility. While GC-MS primarily targets volatile compounds, derivatization (e.g., trimethylsilylation, TMS) enables analysis of highly polar, water-soluble metabolites such as sugars and amino acids. In metabolomics studies, compounds not registered in commercial EI mass spectral databases may also be detected and must be treated as unknown compounds.
To determine the molecular formulas of unknown compounds that are not listed in the database, we propose an “integrated analysis” approach1) that combines electron ionization (EI) and soft ionization (SI) data obtained using a time-of-flight mass spectrometer (TOFMS). Additionally, automated structure estimation can be performed using msFineAnalysis AI, which predicts EI mass spectra from chemical structures using artificial intelligence2).
In this MSTips, non-targeted measurements of metabolites in mouse feces were performed using GC-TOFMS, followed by data analysis using msFineAnalysis AI.