Qualitative analysis by comprehensive 2D GC / TOFMS - Comparison of kerosene and diesel oil

Significance of the Topic

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS) offers exceptional separation power for complex hydrocarbon mixtures. In petrochemical analysis, distinguishing compounds by boiling point and polarity is critical for characterizing fuels, ensuring quality control, and optimizing refining processes.

Objectives and Study Overview

This application note illustrates the qualitative comparison of kerosene and diesel oil using a GC×GC-TOFMS system. The primary goal is to demonstrate the high resolving capability of the JEOL AccuTOF-GC mass spectrometer when paired with a GC×GC setup, enabling rapid and detailed profiling of hydrocarbon distributions in different fuel fractions.

Methodology and Instrumentation

A comprehensive layout of the analytical workflow:

• GC×GC System
  Agilent 6890 GC with ZOEX KT2004 modulator within a single oven to perform heart-cutting between two columns.
• Column Configuration
  First dimension: HP-1ms (30 m × 0.25 mm I.D., 0.25 µm)
  Second dimension: DB-17 (2 m × 0.1 mm I.D., 0.1 µm)
• Temperature Program
  Oven: 50 °C (1 min) → 5 °C/min → 280 °C (6 min)
  Injection: 280 °C, split mode 1:200, 0.5 µL volume
• Carrier Gas
  Helium at constant pressure of 680 kPa
• Modulation
Trapping interval: 6 s

• TOFMS Detection (AccuTOF-GC JMS-T100GC)
  Ionization: EI+ at 70 eV, 300 µA
  Mass range: m/z 35–500
  Acquisition rate: 25 Hz (0.04 s per spectrum)

Results and Discussion

GC×GC contour plots reveal distinct patterns for kerosene (C9–C15) and diesel oil (C11–C15). The first dimension separates components by volatility: kerosene shows a greater abundance of lower-boiling homologues, whereas diesel is enriched in higher-boiling species. The second dimension resolves compounds by polarity, differentiating saturated, unsaturated, and aromatic hydrocarbons. Peak intensity mapping (color scale from light blue to red) highlights major constituents and their relative concentrations.

Benefits and Practical Applications

• Enhanced Selectivity: Two-dimensional separation offers superior discrimination of isomers and structural classes.
• High Throughput: Fast acquisition by AccuTOF-GC ensures no peak loss despite narrow chromatographic signals.
• Improved Sensitivity and Resolution: High mass resolving power permits confident qualitative profiling of complex mixtures.
• Quality Control: Detailed compositional fingerprints support batch consistency, contamination assessment, and product verification.

Future Trends and Potential Applications

Advancements in modulation technology and data processing will further reduce cycle times and enhance peak capacity. Integration with chemometric tools can automate pattern recognition for rapid screening in petroleum refining, environmental monitoring, and forensic investigations. Emerging applications may include real-time process control and remote sensing of volatile organic compounds.

Conclusion

This study demonstrates that GC×GC-TOFMS, when equipped with the AccuTOF-GC detector, provides unparalleled separation and mass spectral acquisition speed for complex fuel analyses. The technique offers a robust platform for detailed hydrocarbon profiling, improving quality assurance and enabling new analytical workflows in petrochemical research.

References

[1] JEOL Ltd. Application Note No. 040/055, 2005.