GC-SCD Analysis of Fuels and Petrochemicals

Significance of the Topic

In fuel production, refining, and petrochemical operations, sulfur compounds are ubiquitous and critically impact catalyst life, corrosion, emissions, and product specifications.
Accurate, selective, and sensitive sulfur analysis is essential to meet tightening environmental regulations and to ensure process efficiency and equipment longevity.

Objectives and Overview

This collection of application studies evaluates the performance of Shimadzu’s Nexis GC-2030 coupled with the SCD-2030 detector across multiple standardized methods.
Key applications include ASTM D5623 for sulfur in light hydrocarbon liquids, sulfur profiling in diesel, ASTM D5504 for natural gas, ASTM D7011 for trace thiophene in benzene (using both helium and nitrogen carriers), IEC 62697-1 for DBDS in transformer oil, and a cross-comparison of sulfur sensitivity versus a flame photometric detector.

Methodology and Instrumentation Used

All analyses employed the Nexis GC-2030 with an innovative horizontal redox SCD-2030 cell, controlled via LabSolutions GC software.
Sample introduction was via split or vaporization injectors (SPL-2030), with helium or nitrogen as carrier gas under constant flow or pressure modes.
Columns ranged from nonpolar Rxi-1ms to polar wax phases and deactivated fused silica for unseparated total sulfur.
Detector gases (H₂, N₂, O₂, O₃) were delivered at optimized flows to sustain stable chemiluminescence reactions.

Main Results and Discussion

ASTM D5623 testing of 19 sulfur compounds in light petroleum yielded ppb-level detection, repeatability (%RSD area < 5%), and linearity (R²> 0.9999) across 0.1–100 ppm.
Diesel fuel analysis showed no matrix suppression, equimolar response factors within 90–120%, and stable detection limits equivalent to pure solvent.
ASTM D5504 natural gas assays detected 14 sulfur species at 50 ppb with %RSD < 1.1% and R²> 0.9999, demonstrating minimal hydrocarbon quenching.
ASTM D7011 benzene thiophene analysis achieved a quantitative limit near 18 ppb, %RSD < 10%, and R²> 0.9999.
Nitrogen carrier gas trials confirmed equivalent sensitivity and linearity to helium, with %RSD < 3% and quantification of trace thiophene.
IEC 62697-1 DBDS in insulating oil was quantified down to 0.1 mg/kg, and total sulfur was determined via the SCD’s equimolar response both with and without chromatographic separation.
Comparisons with an FPD(S) demonstrated that only the SCD maintained consistent sensitivity proportional to the number of sulfur atoms (equimolarity) across diverse compounds.

Benefits and Practical Applications

• High selectivity and ppb-level sensitivity for sulfur species in complex matrices
• Equimolar detector response simplifies calibration and total sulfur quantitation
• Extended stability and reproducibility support long-term monitoring
• Flexibility to operate with nitrogen carrier gas reduces helium dependency and cost
• Compliance with multiple ASTM and IEC standards ensures regulatory adherence

Future Trends and Opportunities

Anticipated regulatory demands for ultra-ultra-low sulfur analysis will drive further sensitivity enhancements and higher throughput.
Advanced GC×GC coupling, real-time process control, and machine-learning deconvolution could deepen sulfur speciation insights.
Expansion of nitrogen carrier gas usage and integrated SCD modules may lower operational costs and environmental impact.

Conclusion

Shimadzu’s GC-SCD configuration delivers a robust, selective, and equimolar detection platform for comprehensive sulfur analysis across fuels, gases, and oils.
Its validated performance across ASTM and IEC methods makes it an ideal choice for routine compliance testing and advanced research applications.

References

• ASTM D5623-95(2018): Sulfur Compounds in Light Petroleum Liquids by GC-SCD
• ASTM D5504-18: Hydrogen Sulfide, Carbonyl Sulfide, Mercaptans, and Sulfides in Natural Gas by GC-SCD
• ASTM D7011-15: Trace Thiophene in Refined Benzene by GC-SCD
• IEC 62697-1: Oil-immersed Electrical Equipment – Sulfur Compound Analysis
• Yan X., J. Sep. Sci., 2006: Selective Nitrogen and Sulfur Chemiluminescence Detectors
• Tanner RL et al., BNL-23103, 1977: Atmospheric Sulfur Sampling and Calibration