Battling Fuel-Washing: Identification and Quantification of Accutrace S10 in Diesel Samples Using a New Benchtop GC-TOFMS System

Significance of the Topic

Government subsidized diesel fuels are marked with dyes to prevent misallocation and fraud. Diesel theft through removal of these dyes, known as fuel-washing, poses significant economic and regulatory challenges. Accutrace S10 is a robust fuel marker designed to resist removal while remaining detectable at trace levels, enabling authorities to enforce subsidy regulations.

Objectives and Study Overview

This study evaluates a rapid and sensitive analytical method for detecting and quantifying Accutrace S10 in diesel samples. By using a new benchtop Pegasus BT GC-TOFMS system coupled with advanced data processing, the aim is to achieve low part-per-billion detection limits, a wide dynamic range, and minimal sample preparation within a 15-minute run time.

Methodology

Commercial diesel samples were spiked with Accutrace S10 standards from 10 to 2500 ppb. Samples underwent full mass range acquisition using Pegasus BT GC-TOFMS. Data processing involved Automated Peak Find with NonTarget Deconvolution to locate the marker in complex matrices, followed by Target Analyte Find focusing on m/z 315 for rapid quantitation.

Used Instrumentation

• Gas chromatograph Agilent 7890 with 7693 liquid autosampler
• Injection: 1 uL pulsed splitless at 250°C
• Carrier gas: Helium at constant flow 1.4 mL/min
• Column: Rxi-5ms (15 m x 0.25 mm x 0.25 µm)
• Oven program: 50°C hold 1.5 min, ramp to 320°C at 34°C/min, hold 4 min
• Transfer line and ion source at 250°C
• Mass spectrometer: LECO Pegasus BT GC-TOFMS, 35–650 m/z, 10 spectra/s

Main Results and Discussion

• The GC-TOFMS method detected Accutrace S10 at concentrations as low as 10 ppb in diesel, with signal-to-noise greater than 10.
• Linear calibration was achieved from 10 to 2500 ppb with correlation coefficient above 0.999.
• Analysis time was under 15 minutes without additional sample cleanup or separation steps.
• Detection sensitivity surpassed the HMRC requirement of 25 ppb by a factor of 2.5.

Benefits and Practical Applications

• The rapid workflow supports high-throughput screening of fuel samples for regulatory and forensic investigations.
• Minimal sample preparation reduces operational complexity and cost.
• High sensitivity enables detection of low levels of subsidy marker even after extensive dilution.

Future Trends and Possibilities for Use

Implementation of benchtop high-resolution GC-TOFMS instruments may expand to field-deployable platforms. Future developments could include multi-marker assays, real-time data analysis, and integration with portable MS for onsite fuel verification. Broader adoption could benefit agricultural, retail, and customs authorities worldwide.

Conclusion

The Pegasus BT GC-TOFMS combined with advanced deconvolution and target analysis provides a fast, robust, and highly sensitive method for quantifying Accutrace S10 in diesel. This approach enhances the capabilities of regulatory bodies to combat fuel-washing and ensure compliance.

Reference

• Christina N Kelly; David E Alonso; Jonathan D Byer; Lorne M Fell; Joseph E Binkley. Battling Fuel-Washing: Identification and Quantification of Accutrace S10 in Diesel Samples Using a New Benchtop GC-TOFMS System, LECO Corporation.