MEASURING BIODIESEL ASTM 7371 and EN 14078 with the Agilent Cary 630 FTIR

Importance of the Topic

Accurate determination of biodiesel content in diesel fuel is critical for quality control, regulatory compliance and optimized engine performance. Fourier transform infrared spectroscopy (FTIR) offers rapid, non-destructive analysis and robust quantification of fatty acid methyl esters (FAME) in middle distillate fuels. Implementing standardized FTIR methods enhances laboratory efficiency and data reliability while reducing analysis time and operational costs.

Objectives and Study Overview

This application note outlines two established FTIR protocols for measuring biodiesel concentration: ASTM D7371 covering 0–100% FAME and EN 14078 for low-level (0–10%) FAME detection. The study demonstrates how the Agilent Cary 630 FTIR system, equipped with interchangeable sampling interfaces and MicroLab PC software, seamlessly implements both methods with minimal user intervention.

Methodology

ASTM D7371 procedure:

• Measurement range: 0–100% biodiesel with three calibration segments (0–10%, 10–30%, 30–100%)
• Use of multi-bounce ZnSe attenuated total reflectance (ATR)
• Calibration based on standards at ultra-high, high and low cetane numbers
• Data processing via partial least squares (PLS) regression

EN 14078 procedure:

• Measurement range: 0–10% biodiesel
• Transmission measurement using a 200 μm pathlength cell
• Evaluation of carbonyl absorbance at 1745 cm⁻¹
• Quantitation by peak-height linear calibration

Used Instrumentation

The key instruments and accessories include:

• Agilent Cary 630 FTIR engine
• 5-bounce ZnSe ATR module for ASTM D7371
• TumblIR 200 μm transmission accessory for EN 14078
• MicroLab PC software with built-in PLS models and conditional reporting
• Portable 4500 and industrial 5500 FTIR analyzers for dedicated turnkey biodiesel analysis

Main Results and Discussion

Both methods were executed with a four-click workflow, guided by intuitive on-screen prompts. The Cary 630 automatically detects the installed accessory and blocks mismatches to prevent errors. Sample preparation checks and automatic background scans ensure data quality. For ASTM D7371, MicroLab PC selects the correct calibration curve and performs PLS calculations automatically. EN 14078 yields rapid linear quantification of FAME via the TumblIR accessory without air-bubble artifacts. Color-coded pass/fail indicators and customizable thresholds streamline result interpretation.

Benefits and Practical Applications

• Fast, reliable biodiesel quantification in both laboratory and field environments
• Reduced analysis time and elimination of complex transmission cells
• Minimized user errors through software-controlled accessory matching and cleanliness verification
• Versatile platform: single FTIR engine supports multiple fuel analyses
• Dedicated portable and industrial analyzers for routine and on-site testing

Future Trends and Opportunities

Emerging developments may include integration of advanced chemometric algorithms for even higher accuracy, real-time process monitoring with online FTIR, cloud-based data management for regulatory reporting, and expanded measurement capabilities for additional fuel adulterants and quality markers. Miniaturized, connected FTIR sensors combined with AI-driven analysis could further revolutionize on-site fuel testing and continuous quality assurance.

Conclusion

The Agilent Cary 630 FTIR system, supplemented by either the ZnSe ATR or TumblIR accessory and MicroLab PC software, delivers a unified solution for measuring biodiesel content according to ASTM D7371 and EN 14078. Portable 4500 and industrial 5500 FTIR analyzers extend these capabilities to field and production environments, offering validated methods and user-friendly workflows that maximize productivity and data integrity.

References

• ASTM D7371: Standard Test Method for Determination of Biodiesel (Fatty Acid Methyl Esters) Content in Middle Distillate Fuels by FTIR
• EN 14078: Determination of Fatty Acid Methyl Esters (FAME) in Middle Distillates by Transmission FTIR
• Agilent Technologies. Measuring Biodiesel Using FTIR Application Note 5991-2241EN, April 2013