Qualitative analysis by comprehensive 2D GC / TOFMS - Analysis of sulfur-contained substances in diesel oil

Significance of the Topic

Comprehensive two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry (TOFMS) offers extraordinary resolving power and rapid data acquisition, essential for profiling trace-level components in complex matrices like diesel oil. Sulfur-containing compounds in fuels affect environmental emissions and engine performance, making their detailed characterization critical.

Objectives and Study Overview

The aim of this application study was to demonstrate qualitative identification of sulfur species in diesel oil using a GC×GC-AccuTOF GC system. High-speed TOFMS detection was evaluated for compatibility with comprehensive GC.

Methodology

• Sample: Diesel oil
• GC×GC system: Agilent 6890 GC with ZOEX KT2004 modulator
• Columns: 1st – HP-1ms (30 m×0.25 mm I.D., 0.25 µm); 2nd – DB-17 (2 m×0.1 mm I.D., 0.1 µm)
• Oven program: 50 °C (1 min) → 5 °C/min → 280 °C (6 min)
• Injection: 0.5 µL split 1:200 at 280 °C
• Carrier gas: He at 680 kPa
• Modulation period: 6 s

Used Instrumentation

• Mass spectrometer: JEOL JMS-T100GC 'AccuTOF GC'
• Ionization: EI+ (70 eV, 300 µA)
• Mass range: m/z 35–500
• Acquisition frequency: 25 Hz (0.04 s)

Main Results and Discussion

• GC×GC-TOFMS chromatograms at m/z 184, 198, and 212 revealed three distinct dibenzothiophene derivatives (A, B, C).
• Accurate mass measurements (sub-mDa accuracy via anthracene internal standard) confirmed molecular formulas: C12H8S, C13H10S, C14H12S.
• Isotopic patterns supported sulfur content assignments; fragment ion at m/z 152 confirmed core structure.

Practical Benefits and Applications

• Enhanced separation power resolves co-eluting species in fuel matrices.
• High-speed TOF detection preserves narrow GC×GC peaks.
• Accurate mass enables definitive identification of trace sulfur compounds, supporting quality control and environmental compliance.

Future Trends and Applications

• Coupling with chemometric and automated data analysis workflows for high-throughput screening.
• Extension to other complex samples such as crude oils, environmental extracts, and petrochemical streams.
• Potential real-time monitoring solutions for industrial process control.

Conclusion

Combining GC×GC with high-frequency TOFMS detection on the AccuTOF GC enabled robust and accurate qualitative profiling of sulfur-containing compounds in diesel, highlighting its value for advanced fuel analysis.