Fatty Acid Methyl Ester Analysis Using the Agilent 8850 GC System

Importance of the Topic

Fatty acid profiling in food and beverages is critical for nutritional assessment, safety regulation, and quality control. Precise measurement of saturated, monounsaturated, polyunsaturated, and trans fatty acids supports dietary balance evaluation, detection of harmful trans fats, and identification of oil adulteration. Gas chromatography (GC) of fatty acid methyl esters (FAMEs) remains the industry standard due to its high resolution and broad applicability.

Objectives and Study Overview

This application note evaluates the performance of the Agilent 8850 GC system in fast, high-resolution analysis of FAMEs. The study aims to demonstrate:

• Rapid separation of 37 common FAMEs on short DB-FastFAME columns using helium (He) and nitrogen (N₂) carrier gases
• Resolution of complex cis/trans and positional isomers of linoleic and linolenic acids on a 90 m DB-FastFAME column and a 100 m HP-88 column
• Impact of carrier gas and column choice on analysis speed, resolution, and precision

Methodology and Instrumentation

Sample Preparation and Chemicals: Four certified FAME mixtures covering C4–C24, trans isomers, linoleic and linolenic esters were prepared in iso-octane or dichloromethane. Standards were diluted appropriately for rapid and detailed separations.
Instrumentation:

• Agilent 8850 GC with split/splitless inlet and flame ionization detector (FID)
• Agilent 7650A automatic liquid sampler (ALS)
• Columns: 20 m and 30 m Agilent J&W DB-FastFAME; 90 m Agilent J&W DB-FastFAME; 100 m Agilent J&W HP-88

Oven Programming and Carrier Gas: Methods were optimized for He and N₂, using rapid temperature ramps (up to 300 °C/min) and constant or ramped column head pressures. Data acquisition was managed by Agilent OpenLab CDS.

Main Results and Discussion

Fast 37-FAME Analysis on Short Columns:

• Under He, 20 m and 30 m DB-FastFAME columns separated 37 FAMEs in <7 min and <10 min, respectively; N₂ methods required <10 min and <15 min
• Key compound pairs met AOAC Method 996.06 resolution criteria (≥1.0); He offered higher resolution and faster run times
• Area repeatability (RSD) ranged from 0.2% to 3.8% and retention time RSD from 0.01% to 0.07%

Complex FAME Mixture Analysis on Long Columns:

• 90 m DB-FastFAME column achieved separation of 52 FAMEs, including cis/trans and positional isomers, in <50 min (He) and <55 min (N₂)
• 100 m HP-88 column required ~75 min; both columns resolved most isomers though one C18:3 cis/trans pair coeluted on HP-88
• Precision on the 90 m column remained excellent (area RSD 0.22–2.7%; RT RSD 0.005–0.041%)

Benefits and Practical Applications

The optimized methods on the Agilent 8850 GC deliver:

• Five- to eight-fold faster FAME profiling for routine nutritional and QC analyses
• High resolution and precision suitable for regulatory compliance and research
• Flexibility to use N₂ in regions with limited He supply, albeit with moderate speed trade-offs

These protocols support high-throughput laboratories in food, beverage, and industrial quality control.

Future Trends and Opportunities

Advances may include:

• Integration of hydrogen carrier gas for further speed enhancement
• Coupling GC with mass spectrometry for detailed isomer identification
• Development of hybrid stationary phases combining speed and selectivity
• Automated sample preparation and data processing for full workflow efficiency

Conclusion

The Agilent 8850 GC system, paired with DB-FastFAME columns, enables ultrafast, high-resolution analysis of FAMEs with excellent precision. Helium-based methods deliver the best performance, while nitrogen provides a viable alternative. The 90 m DB-FastFAME column matches or exceeds traditional HP-88 separations in reduced time, making these methods ideal for routine and specialized fatty acid analyses.

Used Instrumentation

• Agilent 8850 gas chromatograph with split/splitless inlet and FID
• Agilent 7650A automatic liquid sampler (ALS)
• Agilent J&W DB-FastFAME columns (20 m, 30 m, 90 m)
• Agilent J&W HP-88 column (100 m)

References

• Zou, Y.; Wu, H. Improving the Analysis of 37 Fatty Acid Methyl Esters. Agilent Technologies Application Note 5991-8706EN, 2018.
• AOAC International. AOAC Official Methods of Analysis, Method 996.06.
• Peoples Republic of China National Health Commission. GB 5009.168-2016.
• Peoples Republic of China National Health Commission. GB 5009.257-2016.