Wasson Chromatography Corner 27 - April 2013

Importance of the topic

Trace-level analysis of amines in hydrocarbon streams and impurities in high-purity gases is vital for maintaining product quality, protecting downstream catalysts and equipment, and ensuring regulatory compliance in petrochemical, semiconductor, pharmaceutical and analytical industries.

Objectives and overview

This newsletter presents two application studies by Wasson-ECE Instrumentation:

• Quantitative determination of light and heavy amines in ethylene, propylene, butane and pentane using gas chromatography with nitrogen chemiluminescence detection.
• Multi-matrix impurity analysis in eight high-purity gases (CO₂, He, H₂, Ar, O₂, CO, N₂, CH₄) via dual pulse discharge helium ionization detectors on a single GC platform.

Additional sections cover recommended literature for practitioners and upcoming events.

Methodology and instrumentation

The amine analysis employed two GC methods: one for light amines (methylamine through indole) and one for heavier amines, each achieved in under fifteen minutes. A combination of liquid and gas sample valves enabled flexible sample introduction and column backflush to protect column integrity.

High-purity gas impurity analysis used dynamic heart-cutting and two PDHID detectors to separate target analytes from large matrix peaks. Seven tailored methods allowed seamless switching between gas matrices with blank purges and method loading.

Použité instrumentace

• Agilent gas chromatograph with nitrogen chemiluminescence detector (NCD), liquid and gas sample valves, automatic liquid sampler and specially passivated hardware to reduce peak tailing.
• Agilent gas chromatograph equipped with dual pulse discharge helium ionization detectors (PDHID/PDHID), onboard high-purity regulators, helium purifier, passivated tubing, gold ferrules and diaphragm valves for ultra-low detection limits.

Main results and discussion

The amine methods achieved a 0.5 ppm detection limit for nine nitrogen-containing compounds and completed analyses in under thirty minutes. Impurity methods reached 50 ppb detection for permanent gases (H₂, Ar, O₂, N₂, CH₄, CO) and 200 ppb for krypton, with efficient CO₂ heart-cut separation providing clean baselines. Dynamic chromatography and backflush strategies overcame challenges of coelution and matrix tailing.

Benefits and practical applications of the method

These turnkey solutions deliver high sensitivity, rapid throughput and minimal carryover. Versatile software-controlled method switching and robust hardware configurations suit QA/QC labs, R&D in petrochemical processing, semiconductor manufacturing and specialty gas monitoring.

Future trends and potential applications

Advances may include coupling multi-dimensional GC methods with mass spectrometry for structural confirmation, real-time on-line monitoring of process streams, integration with laboratory information management systems (LIMS), and expansion to other trace-level analytes such as sulfur- or oxygen-containing compounds.

Conclusion

Wasson-ECE’s customized GC platforms provide comprehensive, sensitive and efficient solutions for trace amine and high-purity gas impurity analysis, offering significant benefits in speed, resolution and operational flexibility across multiple industries.

Reference

• McNair H., Miller J. Basic Gas Chromatography. John Wiley & Sons, 1998.
• Grob R., Barry E. (eds.). Modern Practices in Gas Chromatography, 4th ed. John Wiley & Sons, 2004.
• Rood D. The Troubleshooting and Maintenance Guide for Gas Chromatographers. Wiley-VCH, 2007.
• Jennings W., Mittlefehldt E., Stremple P. Analytical Gas Chromatography, 2nd ed. Academic Press, 1997.