FUEL MARKER ANALYSIS IN DIESEL FUEL USING 2D-GC/MS

Importance of the topic

Accurate detection of fuel markers in diesel is essential to combat fuel fraud and tax evasion. Governments worldwide lose significant revenue when low-tax fuels intended for agricultural use are illegally laundered and sold as road diesel. A robust analytical method capable of identifying trace levels of an indelible marker helps regulators and laboratories maintain tax compliance, protect public resources, and deter criminal activity.

Objectives and study overview

This study demonstrates a two-dimensional gas chromatography–mass spectrometry (2D-GC/MS) approach for the sensitive and reliable analysis of a novel, laundering-resistant fuel marker in diesel. The goal is to achieve quantitative detection down to low parts-per-billion (ppb) levels via direct injection, while preserving instrument performance over extended sample sequences.

Methodology and instrumentation

The analytical workflow uses direct hot splitless injection of diesel fuel into a GC/MS system equipped with Capillary Flow Technology (CFT) Deans Switch for heart-cutting and post-run back-flush. Only the chromatographic window containing the marker is diverted to the mass spectrometer; bulk hydrocarbons are routed to an FID waste stream. Key instrumentation includes:

• Agilent 7693A Auto-Liquid Sampler
• Agilent 7890B GC with Multimode Inlet, CFT Deans Switch, and Flame Ionization Detector
• Agilent 5977A Single Quadrupole Mass Spectrometer with Extractor Ion Source

Electron impact ionization and Selected Ion Monitoring (SIM) are used to detect marker-specific ions while minimizing solvent and matrix load on the MS source.

Main results and discussion

Calibration over a 25 ppb to 2.5 ppm range (1 %–100 % marker level) yielded a linear response (R² = 0.99995). A 50 ppb (2 %) test sample showed quantitative repeatability below 10 % RSD across 12 injections. Carry-over assessment—injecting a 2.5 ppm standard immediately followed by blank diesel—demonstrated no detectable residual signal, confirming the effectiveness of heart-cutting and back-flush in preventing contamination.

Benefits and practical applications

The presented 2D-GC/MS method offers:

• High sensitivity for trace marker detection
• Extended run times with minimal MS source cleaning
• Direct injection without sample prep for rapid throughput
• Selective heart-cutting to protect MS from matrix overload

This approach is suitable for regulatory laboratories, customs enforcement, and quality control in the fuel industry.

Future trends and potential applications

Advances in two-dimensional separations and high-resolution mass spectrometry may further improve selectivity and detection limits for complex fuel matrices. Automated data processing and integration with laboratory information management systems (LIMS) will enhance throughput and traceability. The methodology can be adapted for other marker compounds or combined with isotope-ratio analysis for strengthened forensic authentication.

Conclusion

The use of a CFT Deans Switch-based 2D-GC/MS system enables robust, sensitive, and reproducible quantification of a laundering-resistant diesel fuel marker at trace levels. By diverting non-target hydrocarbons away from the MS and employing heart-cut and back-flush strategies, the method maintains performance and prevents carry-over, supporting reliable routine screening.

Reference

• Chris Sandy; Agilent Technologies. Fuel Marker Analysis in Diesel Fuel Using 2D-GC/MS. Solution Note, September 2015.