Analysis of Linear Fatty Acids

Significance of the Topic

Linear fatty acids play key roles in nutrition, metabolism, and industrial applications, making their accurate determination essential for food quality control, biochemical research, and environmental monitoring.

Objectives and Overview of the Study

This application note demonstrates a reliable reversed-phase liquid chromatography method for separating and quantifying fourteen straight-chain fatty acids (from C2 to C15) using the Shim-pack GIST C18 column. The work aims to establish operating conditions that provide baseline resolution and reproducible detection suitable for routine laboratories.

Methodology and Used Instrumentation

A gradient elution approach was employed with mobile phase A consisting of 0.1 % phosphoric acid in water and mobile phase B of 0.1 % phosphoric acid in acetonitrile. The gradient program shifted from 90/10 (A/B) to 10/90 over 15 minutes, held for an additional 10 minutes, at a constant flow rate of 1.0 mL/min. Column temperature was maintained at 40 °C and the injection volume was 10 μL. Detection was performed by UV absorbance at 210 nm.

Instrumentation

• Column Shim-pack GIST C18, 150 × 4.6 mm I.D., particle size 5 μm.
• Gradient mixer for mobile phase blending.
• UV detector set to 210 nm.
• Pump and autosampler configured for 10 μL injections.

Main Results and Discussion

The method achieved clear separation of acetic acid (C2) through pentadecanoic acid (C15) within 25 minutes of run time. Early eluting short-chain acids exhibited sharp peaks with minimal tailing, while longer chains displayed increased retention consistent with hydrophobic interactions. The UV 210 nm detection provided sufficient sensitivity for 1 mg/mL standards, demonstrating linear response across the series.

Benefits and Practical Applications of the Method

This straightforward gradient LC method offers high reproducibility and ease of use for laboratories performing fatty acid profiling in food, feed, or biological samples. Its compatibility with standard UV detection and common C18 columns makes it accessible without specialized reagents or detectors.

Future Trends and Potential Applications

Emerging needs in lipidomics and environmental analysis may drive further development toward higher throughput, automated sample preparation, and coupling with mass spectrometry for enhanced selectivity. Miniaturized columns or ultra‐high-performance systems could shorten run times and reduce solvent consumption.

Conclusion

The presented reversed-phase LC method on Shim-pack GIST C18 efficiently separates a wide range of linear fatty acids with reliable accuracy and reproducibility. It serves as a robust protocol for routine analyses in various scientific and industrial settings.

References

• Shimadzu Corporation, ERAS-1000-0210, First Edition December 2021.