Monitoring of Sulfur Components by Simultaneous Analysis Using GC-MS and GC-SCD

Importance of the Topic

The control of sulfur compounds in fossil fuels is critical to prevent environmental pollution and avoid catalyst poisoning in automotive exhaust systems.
Even trace levels of sulfur can impair catalyst performance and lead to increased emissions.

Objectives and Study Overview

This study demonstrates a method to perform simultaneous analysis of sulfur species and general hydrocarbon profiling using a detector splitting system connected to GC-MS and GC-SCD.
The approach enables comprehensive identification of all components while selectively detecting sulfur compounds in a single run.

Methodology

Simultaneous sample introduction to an MS and a sulfur chemiluminescence detector was achieved by splitting the column effluent.
A model mixture of five sulfur standards at 0.1 ppm in isooctane was used for system validation.
Subsequently, a real diesel fuel sample with approximately 300 ppm sulfur content was analyzed under optimized GC conditions.

Used Instrumentation

• Gas chromatograph: Shimadzu GCMS-QP2020 NX
• Detector: Nexis SCD-2030 for sulfur detection and MS with EI ionization
• Detector splitting system: Micro Channel 4-Port Splitter with inert coated parts
• Column: SH-Rxi 1MS (30 m × 0.32 mm I.D., 0.4 μm film thickness)
• Autosampler: AOC-30i
• Carrier gas: Helium flow at 45 cm/s (validation) and 35 cm/s (diesel analysis)
• Temperature program: 50 °C to 330 °C at 15 °C/min

Main Results and Discussion

• Validation at 0.1 ppm confirmed the detection of all five target sulfur compounds, including the highly adsorptive 2,2'-dithiodipyridine.
• In the diesel fuel analysis, the GC-MS total ion chromatogram (TIC) showed numerous hydrocarbon peaks, but sulfur signals were obscured by overlapping compounds.
• The GC-SCD chromatogram selectively revealed sulfur species; a peak at ~6.7 min was identified as di-tert-butyl disulfide via MS library search.
• Combining both detectors allowed identification of low-level sulfur compounds that are often masked in single-detector analyses.

Benefits and Practical Applications

• Rapid screening and quantification of sulfur contaminants alongside full hydrocarbon profiling in one analysis.
• Reduced analysis time and sample usage by dual-detector operation from a single injection.
• Enhanced quality control for fuel production, catalyst development, and environmental monitoring.

Future Trends and Possibilities

• Integration with high-resolution mass spectrometry for detailed structural elucidation of sulfur species.
• Automated data workflows for database-driven identification and quantitation.
• Extension of the splitting approach to other selective detectors, such as nitrogen chemiluminescence.

Conclusion

The combined GC-MS and GC-SCD approach using a detector splitting system provides comprehensive and selective sulfur analysis in a single run.
This method uncovers trace sulfur compounds masked in traditional GC-MS, improving fuel quality assessment and supporting environmental compliance.

References

• Y. Kitamaki, A Study on Sulfur Standard Materials, AIST Bulletin of Metrology, Vol. 4, No. 3, 2006.