Automated Standard and Sample Preparation Using the Agilent 7696A WorkBench for GC/MS Analysis of FAME Contamination in Jet Fuel

Importance of the Topic

The detection of trace fatty acid methyl esters (FAME) in jet fuel is critical to ensure fuel quality and prevent engine damage. FAME contamination arises when multiproduct pipelines transport biodiesel alongside jet fuel. International guidelines set a strict limit of 5 mg/kg total FAME in aviation turbine fuel. Reliable quantitation at low levels demands precise standard and sample preparation to achieve accurate, reproducible GC/MS results.

Objectives and Study Overview

This work demonstrates the automation of calibration standard and sample preparation for FAME analysis in jet fuel using the Agilent 7696A Sample Prep WorkBench, following Energy Institute Method IP585. The study compares manual pipetting with automated WorkBench procedures in terms of linearity, repeatability, and resource consumption.

Methodology and Instrumentation

Calibration standards: Ten working calibration standards covering 2–100 mg/kg FAME were prepared from a 1000 mg/kg working standard solution. Samples: Three jet fuel samples spiked at different FAME levels were prepared in duplicate.

• Sample prep automation: Agilent 7696A WorkBench with dual 7693A injection towers, robotic arm, vortex mixer, and heating station.
• GC/MS analysis: Agilent 5975C GC/MS in splitless mode with HP-INNOWAX column (50 m × 0.2 mm × 0.4 μm) and selective ion monitoring (SIM).

Main Results and Discussion

Automated WorkBench standards exhibited excellent linearity (R² ≥ 0.999) at both low and high calibration ranges, whereas manual high-level standards for C18:2 and C18:3 occasionally failed. Sample repeatability for manual prep in one sample exceeded the IP585 limit (r > 0.7 mg/kg), rendering results invalid. WorkBench-prepared samples consistently met repeatability requirements (r well below method limits). Automated calibration also eliminated the need to remake failing manual standards, accelerating result delivery.

Benefits and Practical Applications

• Reduction of chemical usage by tenfold (100 µL vs. 1 mL manual prep).
• Improved calibration performance and linearity for all FAME analytes.
• Enhanced sample precision and repeatability.
• Minimized human error and variations in pipetting.
• Faster time to result by eliminating rework of failing standards.

Future Trends and Potential Applications

Automation of microvolume liquid handling is expected to expand into other trace contaminant analyses, including additives and degradation products in fuels and lubricants. Advanced robotics and software integration will further improve throughput, real-time quality monitoring, and remote operation. Coupling to high-resolution mass spectrometry could extend the method to novel biofuel contaminants.

Conclusion

The Agilent 7696A WorkBench provides a robust, automated solution for preparing calibration standards and samples for FAME analysis in jet fuel. Automation delivers superior linearity, repeatability, and resource efficiency compared to manual methods and ensures compliance with IP585 requirements.

References

1. IP 585/10 “Determination of fatty acid methyl esters (FAME), derived from bio-diesel fuel, in aviation turbine fuel – GC-MS with selective ion monitoring/scan detection method”, The Energy Institute, London, UK.