Wasson Chromatography Corner 13

Importance of Topic

Accurate quantification of noble gases in air and reactive gases such as hydrogen sulfide and carbon dioxide in amine solutions is crucial for environmental monitoring, industrial process control, and quality assurance. Noble gases serve as tracers in atmospheric studies and validate gas handling systems, while precise measurement of H2S and CO2 ensures effective gas sweetening, odor control, and equipment protection.

Study Objectives and Overview

This report summarizes two analytical approaches developed by Wasson-ECE. The first method targets noble gas analysis in ambient air using an Agilent gas chromatograph with a pulse discharge helium ionization detector (PDHID). The second approach measures H2S and CO2 in methyldiethanolamine (MDEA) solutions via a custom sparge-and-trap system coupled with gas chromatography and thermal conductivity detection (TCD). Method development, system configuration, and performance evaluation are presented.

Methodology

• For noble gases, an Agilent GC with PDHID was configured with dual oxygen scrubbers and liquid nitrogen cryogenic cooling. Two complementary methods alternate scrubber use and bypass O2 removal to separately quantify argon or oxygen, and detect krypton, nitrogen, and xenon within a 30-minute cycle.
• For H2S and CO2, acidified MDEA samples were automatically diluted and sparged with helium. A Nafion membrane drier removed water vapor before analytes were trapped on an ambient temperature adsorption column. Thermal desorption into the GC–TCD provided quantitative analysis in 20 minutes per injection.

Used Instrumentation

• Agilent gas chromatograph
• Pulse discharge helium ionization detector (PDHID)
• Thermal conductivity detector (TCD)
• Liquid nitrogen cryogenic cooler
• Dual oxygen scrubber system with automated valve switching
• Custom sparge-and-trap assembly
• LEAP CTC autosampler with Nafion membrane dryer

Main Results and Discussion

The PDHID configuration reliably detected argon, oxygen, krypton, nitrogen, and xenon at parts-per-million levels, achieving over 100 injections per scrubber before regeneration. Cryogenic focusing resolved krypton from nitrogen interference. The sparge-and-trap system delivered linear, repeatable responses for H2S and CO2 across varied sample volumes, and supported up to 30 analyses per day without co-evolved gas interference.

Benefits and Practical Applications

• Automated, high-throughput analysis for QA/QC and environmental studies
• Enhanced sensitivity through cryogenic trapping and scrubber cycling
• Reduced downtime via redundant scrubber regeneration
• Flexible sparge-and-trap design adaptable to diverse sample matrices

Future Trends and Possibilities

Emerging developments in automated sample processing, miniaturized cooling, and novel detectors are expected to further boost sensitivity and speed. Integration with real-time data analytics, remote monitoring, and cloud-based platforms will streamline environmental surveillance and process optimization. Extending these methods to other trace gases and volatile compounds will expand their industrial and research applications.

Conclusion

Wasson-ECE’s custom-tailored GC solutions with PDHID and TCD detection deliver robust, reproducible performance for challenging gas analyses. The strategic use of oxygen scrubbers, cryogenic cooling, and sparge-and-trap systems enables efficient separation and accurate quantification of noble and reactive gases, addressing critical needs in analytical laboratories.