Methanol in Biodiesel by EN14110 with the HT3 and Versa Automated Headspace Analyzers

Importance of the Topic

The growing demand for renewable energy sources has positioned biodiesel as a sustainable alternative to petroleum diesel. Ensuring the quality and safety of biodiesel involves strict control of residual methanol levels, a byproduct of the transesterification process. Accurate methanol analysis is essential for meeting European standard EN 14110 and ensuring fuel performance and regulatory compliance.

Objectives and Study Overview

This study evaluates the performance of two Teledyne Tekmar automated headspace vial samplers, the HT3 and Versa, in determining methanol content in B-100 biodiesel according to Procedure B of EN 14110. The work compares results using helium and nitrogen as supply and carrier gases and examines resolution, calibration linearity, repeatability, and reproducibility.

Methodology and Instrumentation

Automated headspace sampling (Procedure B) was used to inject 22 mL biodiesel samples and calibration standards containing 0.01, 0.1, and 0.5 % m/m methanol. A FAME reference standard (cleaned to < 0.001 % methanol) served as the matrix. Both samplers employed a 0.5 mL loop, 80 °C vial temperature, 45 min equilibration, and 10 psig pressurization.
Instrumentation used

• Headspace samplers: HT3 and Versa
• Gas chromatograph with flame ionization detector
• Column: Restek Rxi-624Sil MS, 30 m × 0.32 mm ID, 1.8 μm film
• Oven program: 40 °C (5 min), ramp 35 °C/min to 280 °C (2 min)
• Inlet: split 20:1, 150 °C, constant velocity mode
• FID: 280 °C, hydrogen and air flows per standard settings

Main Results and Discussion

Resolution between methanol and 2-propanol exceeded 24 for both samplers and gases, far above the minimum required. Calibration linearity yielded correlation coefficients of 0.9999 or better. Calibration factor variation ranged from 4.8 to 9.7 % RSD. Twenty unwashed biodiesel samples demonstrated repeatability (r) and reproducibility (R) values well within EN 14110 criteria for both helium and nitrogen.

Benefits and Practical Applications

Automated headspace sampling streamlines methanol analysis, reduces manual error, and increases throughput. The HT3 and Versa systems deliver high resolution and precision without internal standards and can integrate with common GC platforms, making them ideal for routine quality control in biodiesel production and regulatory testing.

Future Trends and Potential Applications

Advancements may include real-time online monitoring of volatile contaminants, coupling headspace autosamplers with mass spectrometric detectors for broader analyte panels, and further optimization of gas usage. Automation and data integration will continue to improve laboratory efficiency and traceability.

Conclusion

The Teledyne Tekmar HT3 and Versa automated headspace vial samplers effectively satisfy EN 14110 requirements for methanol determination in biodiesel, offering robust resolution, excellent linearity, and reliable precision using either helium or nitrogen.

References

• ASTM D 6571-12 Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels, ASTM International.
• EN 14214 Automotive Fuels – Fatty Acid Methyl Esters (FAME) for Diesel Engines – Requirements and Test Methods, CEN.
• EN 14110 Fat and Oil Derivatives – Fatty Acid Methyl Esters (FAME) – Determination of Methanol Content, CEN.
• History of Biodiesel Fuel, biodiesel.com.