Determination of Free Glycerol in Fatty Acid Methyl Esters and Biodiesel according to EN 14106

Importance of the Topic

Determination of free glycerol in biodiesel is essential to ensure fuel quality and engine performance. Traces of glycerol can lead to filter clogging, injector fouling and non-compliance with international specifications such as ASTM D6751 and EN 14214. Reliable quantification supports quality control in production and blending operations.

Objectives and Study Overview

This application investigates the performance of a SCION 456 GC-FID system configured according to EN-14106. It aims to validate the method’s accuracy, precision and repeatability for measuring free glycerol content in fatty acid methyl esters (FAMEs) within the specified range of 0.005–0.070% mass.

Methodology and Instrumentation

Sample preparation involved weighing 3.5 g of biodiesel into a test tube, adding 1 mL ethanol, 1 mL 1,4-butanediol (internal standard) and 4 mL hexane followed by gentle mixing and centrifugation. The lower hexane phase was transferred to GC vials for analysis. Calibration standards containing known quantities of glycerol and 1,4-butanediol were used to calculate the glycerol response factor.

• GC system: SCION 456 GC with split/splitless injector at 270 °C (split 75 mL/min)
• Column: SCION PLOT Q, 10 m × 0.32 mm × 0.10 μm
• Oven: 60 °C hold 12 min, ramp 20 °C/min to 120 °C, hold 1 min
• Carrier gas: Helium at 18 psi for 12 min, then ramp to 30 psi
• Detector: FID at 300 °C

Main Results and Discussion

Ten consecutive injections of a certified biodiesel sample yielded an average free glycerol content of 0.0425 % m/m with a relative standard deviation of 0.94 %. This performance falls well within the EN-14106 repeatability requirement of 0.03–0.08 % m/m. Chromatographic separation provided clear resolution between the glycerol and internal standard peaks.

Benefits and Practical Applications

• Ensures compliance with biodiesel fuel standards by precise glycerol measurement
• Supports high-throughput quality control in production environments
• Internal standard methodology enhances robustness across sample batches

Future Trends and Opportunities

• Adoption of automated sample preparation to increase laboratory efficiency
• Coupling GC with mass spectrometry for improved specificity and lower detection limits
• Implementation of real-time, online monitoring for continuous process control

Conclusion

The SCION GC-FID method effectively quantifies free glycerol in biodiesel according to EN-14106, exhibiting excellent repeatability and alignment with EN-14214 requirements. This reliable approach is well suited for routine quality assurance in biodiesel production.

References

No external literature references were provided in the source text.