Solid-phase microextraction and the human fecal VOC metabolome

Area of Science:

• Metabolomics
• Analytical Chemistry
• Gastroenterology

Background:

• Volatile organic compounds (VOCs) in human feces hold diagnostic potential for health implications.
• Headspace solid-phase microextraction (SPME) is a key technique for isolating and analyzing fecal VOCs.
• Previous studies often used a single SPME fiber type, potentially limiting comprehensive metabolomic coverage.

Purpose of the Study:

• To evaluate the efficacy of diverse SPME fiber coatings for comprehensive human fecal VOC metabolomics.
• To identify a minimal set of SPME fibers for optimal metabolite isolation.
• To assess the impact of extraction duration and ex vivo fermentation on fecal VOC profiles.

Main Methods:

• Evaluation of eight different commercially available SPME fibers for fecal VOC extraction.
• Analysis of extracted VOCs using both Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Flame Ionization Detection (GC-FID).
• Assessment of extraction duration and ex vivo enteric microbial fermentation effects.

Main Results:

• A minimal set of five SPME fibers (50/30 µm CAR-DVB-PDMS, 85 µm CAR-PDMS, 65 µm DVB-PDMS, 7 µm PDMS, and 60 µm PEG) collectively isolated approximately 90% of total metabolites.
• Extraction duration did not significantly affect metabolite composition under the described ex vivo conditions.
• Ex vivo enteric microbial fermentation did not alter metabolite composition during prolonged extractions.

Conclusions:

• Employing a combination of diverse SPME fibers is crucial for maximizing the coverage of human fecal VOC metabolomics.
• The identified minimal set of five SPME fibers provides a robust and efficient approach for fecal VOC analysis.
• The described SPME method ensures metabolite stability during prolonged extractions, even with ex vivo fermentation.