Using flow-modulated GC×GC technology coupled with GC-Orbitrap mass spectrometry for the profiling of automotive diesel

Importance of the Topic

Comprehensive two-dimensional gas chromatography (GC×GC) coupled with high-resolution accurate mass spectrometry provides superior separation and identification of complex petroleum matrices such as automotive diesel. This technique overcomes the limitations of one-dimensional GC by resolving coeluting compounds and enabling detailed compositional profiling, critical for quality control, environmental monitoring, and product characterization in petrochemical industries.

Objectives and Study Overview

The study aims to demonstrate the performance of a flow-modulated GC×GC system (Thermo Scientific TRACE 1310 GC with SepSolve INSIGHT modulator) combined with Orbitrap Exploris GC-MS and flame ionization detection for simultaneous acquisition of mass spectrometry and FID data. The paper focuses on aligning retention times across detectors, evaluating reproducibility, and applying PINA classification for n-paraffins, isoparaffins, naphthenes, and aromatics in diesel samples.

Methodology and Instrumentation

• Sample preparation involved direct vials of unaltered diesel fuel
• Separation achieved using a TraceGOLD TG-17SilMS 20 m × 0.18 mm × 0.18 µm first-dimension column and Rxi-5Sil MS 5 m × 0.25 mm × 0.1 µm second-dimension column
• Flow modulation via SepSolve INSIGHT reverse fill/flush module
• Detection by Orbitrap Exploris GC-MS for high-resolution accurate mass data (< 1 ppm) and Instant Connect FID
• Data processing with ChromSpace software for color plots, 3D visualization, and stencil-based PINA grouping

Main Findings and Discussion

• Comprehensive GC×GC delivered enhanced chromatographic resolution, clearly separating coeluting compounds such as propylbenzene and methylcyclohexene in the second dimension
• Simultaneous MS and FID chromatograms were successfully aligned, enabling direct matching of identified peaks with quantitation data
• Stencil-based PINA analysis yielded reproducible percentage areas for n-paraffins, isoparaffins, naphthenes, and aromatics with %RSDs of 0.9 to 3.2 over three days
• Accurate mass measurements allowed confident confirmation of molecular formulas for target analytes (e.g., naphthalene and trimethylbenzene)

Benefits and Practical Applications

• Improved separation power and detection confidence in complex petroleum samples
• Simultaneous qualitative (MS) and quantitative (FID) analysis reduces analysis time and simplifies workflows
• Stencil PINA classification streamlines group quantitation and comparison across samples
• High mass accuracy supports unknown compound identification and elemental formula assignment

Future Trends and Potential Uses

• Integration of GC×GC with advanced informatics for automated peak annotation and library matching
• Extension to other complex matrices such as biofuels, lubricants, and environmental samples
• Development of faster modulator technologies to increase throughput
• Combination with alternative ionization methods for improved detection of polar and labile compounds

Conclusion

Flow-modulated GC×GC combined with high-resolution Orbitrap mass spectrometry and FID offers a powerful analytical platform for detailed profiling of automotive diesel. The approach enhances compound resolution, ensures reproducible quantitation, and delivers accurate mass information for confident identification.

Used Instrumentation

• Thermo Scientific TRACE 1310 Gas Chromatograph
• SepSolve Analytical INSIGHT reverse fill/flush flow modulator
• TraceGOLD TG-17SilMS first-dimension column
• Rxi-5Sil MS second-dimension column
• Thermo Scientific Orbitrap Exploris GC-MS
• Thermo Scientific Instant Connect Flame Ionization Detector
• SGE SilFlow splitter and transfer line
• Thermo Scientific XCalibur Qual Browser

References

1. Phillips JB, Beens J Comprehensive two-dimensional gas chromatography A hyphenated method with strong coupling between the two dimensions Journal of Chromatography A 1999 856 331–347
2. SepSolve Analytical White Paper 007 Technical note Comprehensive two-dimensional gas chromatography Overview of GC×GC
3. Thermo Fisher Scientific Comprehensive analysis of automotive diesel using flow-modulated GC×GC technology coupled with GC-MS Technical Note 000050 2021