PAC SeNse - Sulfur/Nitrogen Selective Detector for Gas Chromatography Applications

Significance of the Topic

Accurate detection of sulfur and nitrogen compounds in petrochemical streams is essential to prevent catalyst deactivation, meet environmental regulations, and optimize refining processes. Chemiluminescence detectors integrated with gas chromatography (GC) provide the selectivity and sensitivity required for speciation at trace levels.

Study Objectives and Overview

This application note presents the PAC SeNse Sulfur/Nitrogen Chemiluminescence Detector, designed for GC analysis. It aims to showcase the detector’s performance characteristics—sensitivity, stability, linearity, and equimolarity—and demonstrate compliance with key ASTM and UOP methods.

Methodology and Instrumentation

The SeNse detector combines GC separation with a chemiluminescence reaction between analyte and oxidizer gases, using either air (for sulfur mode) or oxygen. A constant-pressure base, a redesigned furnace for precise temperature control, and a patented regenerable catalyst probe ensure baseline stability. Automated leak checks and universal GC mounting enable seamless integration.

Used Instrumentation

• SeNse detector configurations: Sulfur only, Nitrogen only, or combined Sulfur/Nitrogen.
• Vacuum pump (115V/230V) and analog interface or input boards for GC connectivity.
• Optional permeation tube module for internal multipoint calibration.

Main Results and Discussion

Performance testing demonstrates:

• Sensitivity below 0.3 pg S/s with air oxidizer and ≤0.15 pg N/s with O2.
• Exceptional baseline stability: RSD ≤2% over 2 hours and ≤3% over 24 and 72 hours.
• Linearity spanning four orders of magnitude with R² >0.999.
• Equimolar response with RSD ≤10% (sulfur) and ≤5% (nitrogen).
• High selectivity: signal-to-background ratios ≥5×10⁷.

Overlay linearity tests using tert-butyl disulfide and thiophene illustrate consistent response factors across three orders of magnitude (RSD ~2%).

Benefits and Practical Applications

• Real-time speciation of sulfur and nitrogen species in fuels and natural gas.
• Compliance with ASTM D5504, D5623, D7011, D7807, and UOP 791 methods.
• Cost-effective operation using laboratory air instead of bottled oxygen in sulfur mode.
• Minimal downtime due to robust catalyst design and controlled furnace temperature.

Future Trends and Opportunities

Advancements may include integrated data analytics for predictive maintenance, expanded heteroatom detection capabilities, miniaturized detector formats for on-line process monitoring, and enhanced automation for high-throughput laboratories.

Conclusion

The PAC SeNse Chemiluminescence Detector delivers leading sensitivity, stability, and equimolarity for sulfur and nitrogen analysis by GC, supporting stringent quality control and regulatory requirements in petrochemical and environmental applications.

References

• ASTM D5504
• ASTM D5623
• ASTM D7011
• ASTM D7807