Overcoming Challenges of Sulfur Analysis in Natural Gas and Gaseous Fuels

Importance of the Topic

The presence and composition of sulfur compounds in natural gas critically influence gas quality, processing workflows and safety. Elevated sulfur levels cause pipeline corrosion, catalyst poisoning and generate harmful emissions when combusted. In addition to refining considerations, controlled addition of sulfur based odorants is essential for leak detection.

Objectives and Overview

This whitepaper evaluates the use of gas chromatography with sulfur chemiluminescence detection for comprehensive sulfur analysis in natural gas and gaseous fuels. A case study applying ASTM D5504 using the Shimadzu Nexis GC-2030 with the SCD-2030 detector is presented, addressing method performance across a range of sulfur species and matrices.

Methodology and Instrumentation

Gas standards comprising 14 sulfur compounds were prepared in high purity nitrogen at ppm and ppb levels, alongside a sulfur free natural gas standard. Samples were injected via a split/splitless injector into a Shimadzu Nexis GC-2030 equipped with a SCD-2030 detector. Sample pathways were treated with inert coating to minimize adsorption and reactivity. Key instrument conditions included carrier gas helium, SH-Rtx-1 capillary column, a large redox cell for complete oxidation and reduction, and an ozone reaction cell for chemiluminescence detection.

Key Results and Discussion

Linearity and repeatability assessments yielded calibration curves with r2 values exceeding 0.9994 and relative standard deviations below 2.31 for all compounds at 50 to 1000 ppb levels. Selectivity tests demonstrated absence of interference from hydrocarbon matrices and consistent detector response in both nitrogen and natural gas backgrounds, confirming resistance to matrix quenching and false peaks.

Benefits and Practical Applications

The redesigned SCD-2030 provides uniform response for sulfur species regardless of boiling point or reactivity, with sensitivity in the low ppb range. Robust detector architecture reduces maintenance, eases operation, and supports high carrier gas flows without compromising performance. Compliance with multiple ASTM methods enables flexible deployment in energy, petrochemical and environmental laboratories.

Future Trends and Opportunities

Advances in detector miniaturization, automated instrumentation and digital data integration will enable real time monitoring of sulfur profiles across processing streams. Emerging low emission regulations and the growth of biogas and hydrogen sectors will drive demand for more sensitive and selective sulfur analysis platforms. Integration of chemiluminescence detection with multidimensional chromatography and portable systems offers potential for on site screening and quality control.

Conclusion

The GC-SCD approach, exemplified by the Shimadzu Nexis GC-2030 with SCD-2030, delivers high sensitivity, selectivity and reliability for sulfur speciation and quantification in natural gas and gaseous fuels. Its robust performance and compliance with standardized methods make it a valuable tool for quality assurance, process control and regulatory adherence.

Reference

• ASTM D5504 Standard Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence
• ASTM D5623 Standard Test Method for Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection
• ASTM D7011 Standard Test Method for Determination of Trace Thiophene in Refined Benzene by Gas Chromatography and Sulfur Selective Detection