GC Analysis of Total Fatty Acid Methyl Esters (FAME) and Methyl Linolenate in Biodiesel Using the Revised EN14103:2011 Method

Significance of GC Analysis of Total FAME and Methyl Linolenate in Biodiesel

Gas chromatography determination of fatty acid methyl esters (FAME) and methyl linolenate is critical for quality assurance of B100 biodiesel. Accurate quantification ensures compliance with European standards, optimizes engine performance, and supports sustainable fuel production.

Objectives and Study Overview

The revised EN14103:2011 method was evaluated on an Agilent 7890A GC platform to:

• Quantify total FAME content in finished biodiesel samples.
• Measure methyl linolenate (C18:3) levels.
• Assess method precision across four biodiesel types: soybean, rapeseed, coconut, and a 50/50 rapeseed–coconut blend.

Methodology and Sample Preparation

Four B100 biodiesel samples were prepared in duplicate. Each aliquot (approx. 100 mg) was spiked with 100 mg methyl nonadecanoate (C19:0) as internal standard, dissolved in toluene, and mixed thoroughly.

Instrument Configuration

The Agilent 7890A GC configuration included:

• Split/splitless inlet with EPC control (100 psi, 250 °C).
• HP-INNOWax capillary column (30 m × 0.25 mm, 0.25 µm).
• Flame ionization detector at 250 °C.
• Agilent 7693 autoinjector.

GC Conditions

Carrier gas: helium at 1 mL/min constant flow
Oven program:

• 60 °C hold for 2 min
• Ramp 10 °C/min to 200 °C
• Ramp 5 °C/min to 240 °C, hold 7 min

Main Results and Discussion

Chromatograms resolved 21 FAMEs from methyl hexanoate (C6:0) to methyl docosahexaenoate (C22:6). A co-elution of methyl behenate (C22:0) and methyl eicosapentaenoate (C20:5) was noted at ~25.58 min.
Typical FAME elution follows increasing carbon number; polyunsaturated esters displayed longer retention due to higher polarity.
Sample analyses showed:

• Total FAME content (wt%) – soybean: 97.4/97.1; rapeseed: 95.6/95.4; coconut: 87.0/87.2; blend: 91.1/91.3.
• Methyl linolenate (C18:3) content (wt%) – soybean: 7.3; rapeseed: 8.3/8.4; coconut: 0.0; blend: 4.1.
• Repeatability (r) values were well within EN14103:2011 specifications for both total FAME and C18:3 determinations.

Benefits and Practical Applications

This GC method:

• Delivers high precision and accuracy across diverse feedstocks.
• Meets or exceeds regulatory repeatability criteria.
• Supports routine QC workflows in biodiesel production facilities.

Future Trends and Potential Applications

Emerging directions include:

• Integration of GC–MS for enhanced compound identification.
• Automation and high-throughput sample handling.
• Miniaturized GC systems for field or on-site testing.
• Advanced data analytics and AI-driven peak integration.

Conclusion

The Agilent 7890A GC paired with EN14103:2011 effectively quantifies total FAME and methyl linolenate in B100 biodiesel. The method demonstrated robust performance and repeatability across multiple feedstocks, making it suitable for routine quality control.

References

1. DIN EN 14105:2011 – Determination of free and total glycerol and mono-, di-, and triglyceride contents in biodiesel. European Committee for Standardization, Brussels.
2. McCurry JD. Agilent 7696A WorkBench Automated Sample Preparation for GC Analysis of Biodiesel Using EN14105:2011. Agilent Technologies; Publication 5990-9893EN; 2012.
3. DIN EN 14103:2011 – Determination of ester and linolenic acid methyl ester content in biodiesel. European Committee for Standardization, Brussels.