Determination of Methanol Content in Biodiesel using Gas Chromatograph with Headspace Sampling According to EN-14110

Importance of the topic

The presence of residual methanol in biodiesel can compromise fuel quality, engine performance, and emission profiles. Reliable quantification of low methanol levels is essential to ensure compliance with international standards and to safeguard the durability of diesel engines.

Objectives and overview of the study

This application note demonstrates the implementation of a headspace gas chromatographic method in accordance with EN-14110 to quantify methanol in fatty acid methyl esters (FAME) at concentrations between 0.01 and 0.5 % (m/m). The study aims to validate the linearity, repeatability, and compliance of the Bruker 430-GC system for routine biodiesel analysis.

Methodology and instrumentation used

• Sample preparation: 1 mL aliquots of calibration solutions (0.5, 0.1, and 0.01 % methanol in FAME) or biodiesel samples were weighed into 20 mL vials and capped promptly.
• Instrumentation:
  • Gas chromatograph: Bruker 430-GC with split/splitless injector (250 °C) and FID detector (275 °C).
  • Headspace sampler: SHS-40 Headspace Analyzer, 1 mL sample loop, vial heating at 80 °C for 45 min.
  • Column: BR-1 fs, 30 m × 0.32 mm, 3.0 μm film thickness.
  • Carrier gas: Helium at 2.0 mL/min constant flow.
  • Oven program: 80 °C isothermal for 0.5 min, ramp at 20 °C/min to 160 °C, hold 2 min.
  • Data handling: Compass CDS software.

Results and discussion

Linearity was confirmed across the calibration range, yielding a correlation coefficient of 0.9998, exceeding the 0.95 requirement. Headspace chromatograms displayed clear methanol peaks without interference from FAME components. A representative biodiesel sample showed a methanol content of 0.038 % (m/m), well below the EN-14214 limit of 0.2 % (m/m). Repeatability tests (n=15) resulted in a relative standard deviation of 1.96 %, within the method’s specified window.

Benefits and practical applications

• High sensitivity and specificity for methanol in biodiesel matrices.
• Minimal sample preparation and rapid throughput.
• Compliance with EN-14110 and EN-14214 regulatory requirements.
• Suitability for quality control in industrial and research laboratories.
• Improved engine safety by ensuring methanol removal.

Future trends and possibilities of use

Emerging developments may include automated sample introduction, integration of mass spectrometric detection for enhanced specificity, and miniaturized headspace modules for field testing. Advances in green analytical chemistry may lead to alternative solvents and reduced sample volumes.

Conclusion

The Bruker 430-GC coupled with the SHS-40 headspace sampler provides a robust, reliable, and standardized solution for quantifying low levels of methanol in biodiesel. The method meets international requirements and is well suited for routine quality assurance.

References

• EN-14110: Fat and oil derivatives – Fatty Acid Methyl Esters (FAME) – Determination of methanol content.
• EN-14214: Automotive fuels – Fatty Acid Methyl Esters (FAME) for diesel engines – Requirements and test methods.