Analysis of Short-Chain Fatty Acids

Significance of the Topic

The profiling of short-chain fatty acids (SCFAs) such as acetic, propionic, isobutyric, butyric, isovaleric and valeric acids is essential for understanding gut microbiota function, assessing food and beverage quality, and monitoring environmental processes.

Objectives and Overview of the Study

This application note presents a robust ion‐exclusion liquid chromatography method for rapid separation and quantification of six SCFAs. Two Shim-pack columns (Fast‐OA and SCR‐102H) are compared to demonstrate performance in terms of speed and resolution.

Methodology

An isocratic elution approach employs 5 mmol/L p-toluenesulfonic acid as the mobile phase. A pH buffering solution containing 5 mmol/L p-toluenesulfonic acid, 20 mmol/L Bis-Tris and 0.1 mmol/L EDTA ensures consistent ion‐exclusion behavior. Separation is achieved at 50 °C with a flow rate of 0.8 mL/min and a 10 µL injection volume. Retention times span 2–20 minutes for all six analytes.

Instrumentation

• Shimadzu HPLC system equipped with conductivity detector CDD-10Avp
• Shim-pack Fast-OA column (100 mm×7.8 mm I.D., 5 µm) with guard
• Shim-pack SCR-102H column (300 mm×8.0 mm I.D., 7 µm) with guard

Main Results and Discussion

Both columns achieved baseline separation of the six SCFAs. The Fast-OA column delivered rapid analysis within 10 minutes, while the SCR-102H column provided enhanced resolution over a 20-minute run. Peak shapes were sharp and symmetry was maintained across analytes, demonstrating reliable quantification.

Benefits and Practical Applications

• High throughput with minimal run times
• No derivatization required, simplifying sample preparation
• Direct conductivity detection for cost‐effective quantitation
• Applicability in clinical, food safety, fermentation and environmental laboratories

Future Trends and Opportunities

Advancements may include coupling with mass spectrometry for lower detection limits, adoption of smaller‐particle columns or microfluidic formats for ultra‐fast separations, and integration into automated workflows for large‐scale screening.

Conclusion

The described ion‐exclusion method using Shim-pack Fast-OA and SCR-102H columns offers a robust, efficient and user‐friendly approach for routine SCFA analysis across diverse application areas.

Reference

Shimadzu Corporation. Application News L555. First Edition: December 2021, ERAS-1000-0153A.