Analyze Permanent Gases and Light Hydrocarbons with Agilent J&W Particle Trap Columns

Significance of the Topic

Understanding the composition of permanent gases and light hydrocarbons is essential in petrochemical, energy and environmental sectors. Accurate quantitation of H₂, O₂, N₂, CO, CO₂ and C₁–C₂ hydrocarbons supports process optimization, safety controls and regulatory compliance. Valve-switching GC methods with particle-trap columns enhance analytical reliability and throughput for quality assurance and process monitoring.

Objectives and Study Overview

This work evaluates Agilent J&W PoraBOND Q PT and CP-Molsieve 5Å PT particle trap columns in GC/TCD analyses of permanent gases and light hydrocarbons. Using helium and argon carriers in a two-valve configuration, the study assesses separation performance, repeatability and stability under isothermal and temperature-programmed conditions.

Methodology and Instrumentation

Analyses were conducted on an Agilent 7890A GC equipped with a thermal conductivity detector. A 10-port sampling valve isolates light analytes and backflushes heavier species, while a 6-port column-isolation valve alternates CP-Molsieve and PoraBOND columns in and out of the carrier stream. Both isothermal (40 °C for helium, 70 °C for argon) and temperature ramps (40 °C→120 °C at 40 °C/min) were tested to optimize run time and resolution.

Used Instrumentation

• Agilent 7890A GC with TCD detector
• PoraBOND Q PT column (25 m×0.53 mm, 10 µm, dual traps)
• CP-Molsieve 5Å PT column (50 m×0.53 mm, 50 µm, dual traps)
• HayeSep Q packed pre-column (3 ft×1/8 in, UltiMetal)
• 10-port and 6-port valves with adjustable restrictor

Main Results and Discussion

Helium carrier at 40 °C achieved baseline separation of all gases within 14 min; temperature programming reduced analysis to 12 min with minimal resolution loss. Over 250 injections in five days, peak area RSDs remained below 0.5% and retention time variation under 0.06%, demonstrating excellent intra- and inter-day precision. Argon carrier improved hydrogen sensitivity, delivering positive H₂ peaks with high signal-to-noise while retaining adequate detection of other gases.

Benefits and Practical Applications

Integrated dual-ended particle traps prevent phase shedding and valve contamination, eliminating signal spikes and maintenance downtime. The dual-column, dual-valve configuration offers high resolution, rapid cycle times and robust operation for process control, natural gas analysis and environmental monitoring.

Future Trends and Applications

Growing demands in the hydrogen economy, biogas quality control and carbon capture drive the need for enhanced sensitivity and faster analyses. Developments in alternative carrier gases, miniaturized valves and automated data processing will further advance permanent gas and light hydrocarbon profiling.

Conclusion

Agilent J&W PLOT PT columns with integral particle traps deliver reliable, repeatable GC/TCD analysis of permanent gases and light hydrocarbons. The system provides exceptional resolution, stability and flexibility with both helium and argon carriers, making it an ideal choice for valve-switching applications.

References

• ASTM D2504-88, Standard Test Method for Noncondensable Gases in C₂ and lighter Hydrocarbon Products by Gas Chromatography, ASTM, 2010.
• ASTM D1946-90, Standard Practice for Analysis of Reformed Gas by Gas Chromatography, ASTM, 2011.
• Anon., Protect your GC system from PLOT column phase shedding, Agilent Technologies Brochure 5991-1174EN, 2012.
• P. Sasso, PLOT PT GC Columns with Integral Particle Traps Separate Gases without Particle Shedding, Agilent Technologies Application Note 5991-2975EN, 2013.