Determination of FAME in Biodiesel blends using FTIR

Importance of the Topic

Biodiesel, made of fatty acid methyl esters (FAME), offers a renewable, low-sulfur, low-toxicity fuel alternative with superior lubrication and reduced particulate emissions compared to petrodiesel.

Accurate quantification of FAME content in diesel blends is critical for meeting regulatory standards, ensuring engine performance, and monitoring production processes.

Objectives and Study Overview

This work demonstrates a fast, precise method for determining FAME concentration in diesel blends by infrared spectroscopy following DIN EN 14078.
Key goals include establishing a simple measurement workflow, achieving high sensitivity down to 0.02% m/m, and enabling use by non-specialist operators.

Methodology and Instrumentation

FAME quantification relies on the carbonyl absorption band near 1745 cm⁻¹, which is unique to esters and absent in hydrocarbon-based petrodiesel. A univariate calibration derived from the Beer–Lambert law correlates absorbance to FAME concentration.

Used Instrumentation

• Bruker ALPHA II FTIR spectrometer with RockSolid™ interferometer and diode laser
• Liquid flow-through cell with 100 µm and 500 µm spacers
• Optional INVENIO or VERTEX FTIR systems
• Dedicated FAME-wizard software for guided operation, dilution correction, path length recognition, calibration management, and autosampler control

Results and Discussion

Calibration with a 100 µm cell over 0–5% m/m FAME shows excellent linearity (R²=0.9999) and a standard deviation of 0.017% m/m. Using a 500 µm cell, the method achieves detection as low as 0.02% m/m with R²=1.0000 and a standard deviation of 0.003% m/m.

Measurement time including background correction is under four minutes. The FAME-wizard automatically applies device corrections, identifies path length, selects the appropriate calibration, and delivers results in % (m/m and v/v) and g/L.

Benefits and Practical Applications

• Rapid and reliable analysis complying with DIN EN 14078
• Minimal sample preparation and straightforward dilution step
• User-friendly interface allowing untrained personnel to perform measurements
• Potential for full automation with an autosampler

Future Trends and Potential Applications

Integration with advanced automation platforms and high-throughput screening in production environments
Expansion to other biofuel blends and related quality control assays
Application of chemometric models to improve multicomponent analysis and robustness against matrix variability

Conclusion

FTIR analysis using a flow-through cell and dedicated software provides a fast, accurate, and user-friendly method for FAME determination in diesel blends. The approach meets regulatory requirements, offers high sensitivity, and supports automation for routine quality control.

Reference

Bruker Application Note AN M60
DIN EN 14078: Fatty acid methyl esters determination in diesel fuel by infrared spectrometry