Increased sensitivity and reproducibility in the analysis of trace fatty acid methyl esters in jet fuel

Importance of the Topic

The reliable detection of trace fatty acid methyl esters (FAMEs) in jet fuel is critical for ensuring fuel quality, preventing microbial contamination, and maintaining engine performance. Traditional WAX-type GC columns suffer from high bleed and limited temperature range, compromising sensitivity and long-term reproducibility. The Agilent J&W DB-HeavyWAX column addresses these challenges by offering ultralow bleed and extended thermal stability, enabling more accurate FAME analysis according to Energy Institute Method IP 585.

Objectives and Overview

This study evaluates the performance improvements achieved when coupling the Agilent J&W DB-HeavyWAX column with the IP 585 protocol for trace FAME analysis in jet fuel. Key goals include comparing column bleed, signal-to-noise (S/N) ratios in SIM and scan modes, and assessing retention time stability over extended operation at elevated temperatures.

Methodology and Instrumentation Used

Sample preparation followed IP 585, preparing calibration standards in hexane at 2–75 mg/g. FAME mixtures were injected and analyzed by both FID and GC/MS.

• Gas chromatograph: Agilent 7890B GC with split/splitless inlet and FID detector
• Mass spectrometer: Agilent 7010 triple quadrupole MSD operated in SIM/scan mode
• Autosampler: Agilent 7693
• Column: Agilent J&W DB-HeavyWAX (60 m × 0.25 mm, 0.50 µm film thickness)
• Carrier gas: Helium, constant flow (12 mL/min)
• Oven program: Isothermal hold at 150 °C, ramp to 200 °C at 12 °C/min, then to 252 °C at 3 °C/min
• FID conditions: 280 °C, H₂ 30 mL/min, air 400 mL/min, makeup 25 mL/min
• MSD conditions: Source 230 °C, quadrupole 150 °C, mass range 33–320 amu, SIM dwell times optimized per analyte

Main Results and Discussion

• Column Bleed: FID measurements at 252 °C showed a bleed of 3.1 pA for DB-HeavyWAX versus 8.8 pA for a conventional WAX column, yielding a lower baseline and cleaner spectra.
• Signal-to-Noise: In SIM mode at 25 mg/g, the DB-HeavyWAX column delivered S/N ratios up to 220 for C16:0–C18:0 compounds, roughly double those observed on the traditional column. At 2 mg/g, analytes remained detectable in both scan and SIM modes.
• Reproducibility: Over 200 injections and 50 hours of continuous operation at 260 °C, retention times for seven FAMEs exhibited %RSD values below 0.15 %, demonstrating exceptional thermal robustness and retention time stability.

Benefits and Practical Applications

The ultralow bleed and extended temperature capability of the DB-HeavyWAX column enhance sensitivity and quantitation accuracy for trace FAMEs in jet fuel. Its ruggedness reduces the need for frequent SIM window adjustments and column replacement, improving laboratory throughput. This makes the method particularly valuable for QA/QC laboratories monitoring biodiesel contamination in aviation fuels.

Future Trends and Opportunities

Emerging demands for advanced biofuel blending and stricter regulatory limits on FAME content will drive further optimization of GC/MS methods. Potential developments include coupling DB-HeavyWAX columns with high-resolution mass spectrometry for improved compound confirmation, exploring faster temperature programs for higher throughput, and integrating automated data processing workflows for real-time monitoring.

Conclusion

The Agilent J&W DB-HeavyWAX column, when used with Energy Institute Method IP 585, significantly improves the analysis of trace FAMEs in jet fuel. Its ultralow bleed, higher S/N ratios, and outstanding retention time stability at elevated temperatures enable sensitive, reproducible quantitation over extended use. This approach enhances analytical performance in fuel testing and supports robust quality control workflows.

References

1. McCurry J. GC/MS Analysis of Trace Fatty Acid Methyl Esters in Jet Fuel Using Energy Institute Method IP585. Agilent Technologies; 2011.
2. Abercrombie V, Provoost L. Increased Thermal Stability and Maximum Temperature of the Agilent J&W DB-HeavyWAX Column. Agilent Technologies; 2018.