Comprehensive analysis of automotive diesel using flow-modulated GC×GC technology coupled with GC-MS

Importance of the Topic

Comprehensive two-dimensional gas chromatography (GC×GC) with flow modulation significantly enhances the separation of complex mixtures such as automotive diesel by combining two column phases and modulator technology. This approach addresses coelution challenges inherent to one-dimensional GC and supports comprehensive profiling of diverse hydrocarbon classes.

Goals and Study Overview

The study demonstrates the integration of the SepSolve INSIGHT flow modulator with the Thermo Scientific TRACE 1310 GC coupled to ISQ 7000 and Orbitrap Exploris mass spectrometers, alongside flame ionization detection (FID). Objectives include achieving full chemical characterization of diesel samples with high chromatographic resolution and mass accuracy.

Methodology and Instrumentation

The flow-modulated GC×GC setup employed:

• SepSolve INSIGHT flow modulator with a 50 µL loop and 4.5 s modulation time
• First-dimension column: TraceGOLD TG-17SilMS (20 m × 0.18 mm × 0.18 µm)
• Second-dimension column: Rxi-5Sil MS (5 m × 0.25 mm × 0.1 µm)
• Detectors: FID (100 Hz acquisition), Thermo ISQ 7000 single quadrupole MS, Orbitrap Exploris GC-MS (7,500 resolution at m/z 200)
• Carrier gas: Helium at 0.5 mL/min (1D) and 20 mL/min (2D)
• Oven program: 40 °C to 300 °C at 2.5 °C/min, total run time 109 min

Main Results and Discussion

GC×GC delivered an order-of-magnitude increase in peak capacity. Coeluting compounds like propylbenzene and methylcyclohexene were fully resolved in the second dimension. Combined MS and FID data were aligned to match identifications and quantitation. PINA grouping of paraffins, isoparaffins, naphthenes, and aromatics streamlined hydrocarbon class analysis. Triplicate injections over three days yielded retention time RSDs below 1.2% and group area RSDs under 3.2%. High-resolution accurate mass data (<1 ppm mass error) confirmed molecular formulas for key analytes such as naphthalene and trimethylbenzene.

Benefits and Practical Application

• Enhanced resolution reduces sample preparation and fractionation steps
• Simultaneous acquisition of FID and MS data enables robust quantitation and identification
• Automated stencil-based grouping accelerates class composition analysis
• High reproducibility ensures reliable QA/QC in petrochemical testing

Future Trends and Opportunities

Advances may include broader adoption of flow-modulated GC×GC in environmental monitoring, integration with machine-learning for peak deconvolution, expansion of high-throughput HRAM screening, and application to emerging biofuels and complex matrices beyond diesel.

Conclusion

The flow-modulated GC×GC platform with simultaneous FID and MS detection offers a powerful solution for comprehensive diesel analysis, combining superior chromatographic resolution, reproducibility, and mass accuracy for confident compound identification and quantitation.

References

1. Phillips JB, Beens J. Comprehensive two-dimensional gas chromatography: A hyphenated method with strong coupling between the two dimensions. J Chromatogr A. 1999;856:331–347.
2. Panic O, Gorecki T. Comprehensive two-dimensional gas chromatography (GC×GC) in environmental analysis and monitoring. Anal Bioanal Chem. 2006;386:1013–1023.
3. SepSolve Analytical. White Paper 007: Technical note: Comprehensive two-dimensional gas chromatography.
4. Bertsch W. Two-dimensional gas chromatography: Concepts, instrumentation, and applications – Part 1: Fundamentals and selected applications. J Sep Sci. 1999;22:647–665.