Wasson Chromatography Corner 6

Significance of the Topic

Refinery gas analysis and trace sulfur speciation are critical for ensuring fuel quality, regulatory compliance, and environmental protection. In parallel, the detection of low‐level impurities in polymer feedstocks directly impacts polymer performance and downstream processing. Advanced chromatographic techniques combining multiple detectors enable comprehensive profiling of complex gas and liquid matrices in a single run, reducing analysis time and improving data reliability.

Aims and Scope of the Studies

This newsletter describes two key applications developed by Wasson-ECE: extended refinery gas analysis with trace sulfur quantification, and GC/MS/FID screening of impurities in polymer‐grade monomers and solvents. In each case, the goal was to integrate multiple detector technologies on an Agilent 7890A platform to achieve rapid, sensitive, and accurate multi‐component analysis.

Methodology and Instrumentation

Both applications employed an Agilent 7890A gas chromatograph configured with different detector arrays:

• Flame Ionization Detector (FID) for C1–C5 paraffins and olefins
• Dual Thermal Conductivity Detectors (TCD/TCD) for permanent gases (CO2, O2, N2, CH4, CO, H2, He, etc.)
• Sulfur Chemiluminescence Detector (SCD) for H2S, COS, methyl and ethyl mercaptans and total sulfur summation
• 5975 Mass Selective Detector (MSD) for trace sulfur and oxygenate speciation in polymer feedstocks, operated in SCAN and SIM modes

Sample introduction varied by application: multi‐port valves and pressurized gas loops for refinery gas streams, on-board vaporizer above 63 °C for liquid monomers, and gas sample valves for ethylene. Four injection methods (A–D) were employed for polymer matrix analyses to separate oxygenates, sulfurs, and C1–C4 hydrocarbons.

Main Results and Discussion

Refinery gas analyses were completed in approximately 15 minutes, with full separation of light hydrocarbons, permanent gases, and sulfur species in a single sequence. The integrated SCD enabled speciation down to low ppm levels while the dual TCDs and FID quantified major gas components. Polymer feedstock screening achieved detection limits of 0.1–100 ppm for 58 targeted impurities in a 20 minute run per matrix, demonstrating reliable retention time identification and quantitation using combined MSD/FID detection.

Benefits and Practical Applications

By consolidating multiple detectors on one GC platform, laboratories gain:

• Reduced analysis time and instrument footprint
• Improved sensitivity and selectivity for sulfur and trace organics
• High throughput with consistent repeatability
• Comprehensive data for QA/QC, environmental compliance, and process control

These methods support refiners in meeting stringent sulfur limits and polymer producers in maintaining feedstock purity to optimize product performance.

Future Trends and Potential Uses

Emerging directions include:

• Automated sample preparation and valve switching to further reduce hands-on time
• Micro- and nano-column technologies for faster separations and lower carrier gas consumption
• Advanced data analysis with chemometrics and AI for real-time process monitoring
• Portable GC systems with modular detector arrays for field applications in environmental and industrial settings

Conclusion

Wasson-ECE’s integrated GC solutions demonstrate that combining FID, TCD, SCD, and MSD on a single Agilent 7890A platform can deliver robust, multi‐component analyses of refinery gases and polymer feedstocks with high sensitivity and rapid turnaround. These configurations enhance laboratory efficiency, ensure regulatory compliance, and pave the way for continued innovation in chromatographic analysis.