Biodiesel quality assessment: determination of esters and linolenic acid methyl ester content in biodiesel (B100) by GC-FID, according to EN 14103

Significance of Topic

Biodiesel (B100) is a renewable, biodegradable fuel derived from vegetable oils via transesterification. Ensuring its quality is crucial for engine performance, emissions control, and compliance with international standards. Accurate quantification of fatty acid methyl esters (FAMEs) and the unsaturated linolenic acid methyl ester content underpins the cetane index and overall fuel specifications.

Aims and Scope of Study

This application note demonstrates the suitability of the Thermo Scientific™ TRACE™ 1610 GC system combined with the TriPlus™ RSH SMART autosampler for quantitative determination of total FAMEs and linolenic acid methyl ester in pure biodiesel, following the EN 14103 standard.

Used Instrumentation

• TriPlus RSH SMART Advanced autosampler: automated sample handling and internal standard addition
• Thermo Scientific™ TRACE™ 1610 GC: iConnect™ split/splitless injector (HeSaver-H2Safer™ mode) and iConnect™ FID
• TRACE TR-BioDiesel GC column (30 m × 0.25 mm × 0.25 µm)
• Chromeleon™ 7.3 Chromatography Data System

Methodology

Samples (125 mg biodiesel) were spiked with 50 mg nonadecanoic acid methyl ester internal standard, diluted in 5 mL toluene, and processed by the SMART autosampler. A 1 µL injection was performed on the TRACE 1610 GC equipped with H2Safer technology. Hydrogen at 2.5 mL/min served as carrier gas; the oven temperature ramped from 60 °C to 240 °C over 37.6 min. FAMEs from C6:0 to C24:1 were separated and detected by FID. Quantitation followed EN 14103 equations using theoretical correction factors.

Main Results and Discussion

The assay achieved average total FAME content of 98.68% (m/m) and linolenic acid methyl ester of 7.03% (m/m), within EN 14103 specifications. No endogenous nonadecanoic ester or co-eluting peaks were observed. Repeatability over 19 replicates met method r-values for both total esters and linolenic ester. Carry-over tests (40 injections) showed no detectable residual peaks in solvent blanks.

Practical Benefits and Applications

• Automated internal standard addition reduces manual error and consumable waste.
• H2Safer technology enables safe, cost-effective hydrogen carrier use without additional sensors.
• Reliable chromatographic separation and data integrity via Chromeleon CDS.

Future Trends and Possibilities

High-throughput FAME analysis may leverage shorter columns and faster temperature ramps. Integration with mass spectrometry could enhance compound identification. Green chromatographic practices will favor renewable gases and miniaturized systems. Real-time monitoring and inline quality control are emerging applications in biodiesel production.

Conclusion

The combination of TRACE 1610 GC and TriPlus RSH SMART autosampler delivers robust, precise quantitation of FAMEs and linolenic ester in biodiesel per EN 14103. The workflow ensures compliance, safety, and efficiency for routine QC laboratories.

References

• ASTM D6584-21: Determination of monoglycerides, diglycerides, triglycerides, and glycerin in B-100.
• EN 14105:2021: FAMEs – Free and total glycerol and mono-, di-, triglyceride determination.
• EN 14110:2020: FAMEs – Methanol content determination.
• EN 14103:2020: FAMEs – Ester and linolenic acid methyl ester content determination.
• Thermo Fisher Scientific AN001897: Automated analysis of free and total glycerol in biodiesel (EN 14105/ASTM D6584).
• Thermo Fisher Scientific AN001898: Headspace analysis of residual methanol in biodiesel (EN 14110).
• EN 14214:2012 (A2:2019): FAMEs for diesel engines – requirements and test methods.
• Thermo Fisher Scientific TN001218: Gas conservation for GC carrier gases.
• Thermo Fisher Scientific AN001225: High-throughput FAME derivatization in oils and fats.