Qualitative analysis by comprehensive 2D GC / TOFMS - Analysis of polycyclic aromatic hydrocarbons in kerosene

Significance of the Topic

Comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC-TOFMS) offers unparalleled separation power and rapid detection for complex mixtures. Its application to polycyclic aromatic hydrocarbons (PAHs) in kerosene demonstrates its value in environmental monitoring, petrochemical quality control and research settings.

Objectives and Study Overview

The primary aim was to perform qualitative profiling of PAHs in kerosene using a GC×GC-TOFMS workflow. The study illustrates how the high peak capacity of GC×GC combined with the fast acquisition and high mass resolution of the AccuTOF-GC enables confident identification of tri- and tetra-cyclic aromatic compounds.

Methodology

The workflow involved two GC separations in series, employing a modulator to transfer narrow elution slices from a non-polar column to a mid-polarity column. Key steps included:

• First-dimension column: HP-1ms (30 m × 0.25 mm I.D., 0.25 μm film)
• Second-dimension column: DB-17 (2 m × 0.10 mm I.D., 0.10 μm film)
• Oven temperature program: 50 °C (1 min) ramping at 5 °C/min to 280 °C (6 min hold)
• Injection: Split (1:200), 0.5 µL at 280 °C
• Carrier gas: Helium at constant 680 kPa
• Modulation period: 6 s

Instrumentation Used

• GC system: Agilent 6890 with ZOEX KT2004 GC×GC modulator
• MS detector: JEOL JMS-T100GC “AccuTOF-GC”
• Ionization: Electron ionization at 70 eV, 300 µA
• Acquisition range: m/z 35–500
• Spectrum acquisition rate: 25 Hz (0.04 s intervals)

Main Results and Discussion

GC×GC-TOFMS yielded two-dimensional chromatograms in which the first axis separated compounds by volatility and the second by polarity. Color-coded intensities highlighted individual peaks, with red indicating the highest signals. Key findings:

• Clear separation of saturated, mono-, and polycyclic aromatic hydrocarbons in kerosene matrix.
• Mass chromatograms at m/z 178 and 202 revealed distinct regions for anthracene and pyrene.
• High-speed acquisition captured narrow GC×GC peaks without loss of spectral fidelity.

The combination of fast spectral recording and high resolving power facilitated reliable identification of target PAHs even in a complex hydrocarbon background.

Benefits and Practical Applications

This GC×GC-TOFMS approach delivers:

• Enhanced separation capacity for isomers and homologous series.
• Rapid qualitative screening suitable for routine QA/QC in petroleum and environmental labs.
• Robust detection of trace aromatic pollutants, fragrances or matrix-rich samples.

Future Trends and Applications

Advancements may include modulation technology improvements, higher-speed detectors and integration of chemometric or machine-learning algorithms to:

• Automate peak deconvolution and compound identification.
• Extend applications to emerging contaminants in water, air and food safety.
• Couple GC×GC with alternative ionization methods for broader chemical coverage.

Conclusion

The study confirms that GC×GC-TOFMS using the JEOL AccuTOF-GC achieves high-resolution qualitative analysis of PAHs in kerosene. Its speed, sensitivity and separation power make it a valuable tool for complex mixture characterization.

Reference

No literature references were provided in the original document.