Wasson Chromatography Corner 2

Importance of the Topic

Carbon dioxide quality directly impacts the safety, flavor, and consistency of carbonated beverages, while accurate ammonia measurement ensures efficient and safe refinery operations. Reliable chromatographic analysis is essential for monitoring trace contaminants and maintaining industry standards.

Study Objectives and Overview

This newsletter issue presents two applied studies:

• Quantification of trace impurities in beverage-grade carbon dioxide to meet beverage industry purity requirements.
• Determination of low-level ammonia and related sulfur compounds in refinery gas streams to verify water wash efficiency and prevent process upsets.

Methodology

Two distinct GC-based workflows were designed:

• Beverage CO2 analysis employed two custom GCs: one with dual flame ionization detectors (FIDs) and a mass selective detector (MSD) for volatile hydrocarbons and BTEX at ppb levels, and a second with sulfur chemiluminescence detector (SCD) plus cryogenic cooling and pulsed discharge helium ionization detector (PDHID) for sulfur compounds and permanent gases in low ppm.
• Ammonia analysis used an Agilent 6890N Refinery Gas Analyzer fitted with a nitrogen chemiluminescence detector (NCD) for NH3 at 1 ppm LDL, plus a separate Agilent 6850 GC with flame photometric detector (FPD) for H2S down to 0.5 ppm.

Used Instrumentation

• Agilent 6890N Refinery Gas Analyzer with NCD
• Agilent 6850 Series GC with FPD
• Custom dual-FID and MSD GC setup
• GC with SCD, cryogenic cooling, and PDHID
• Split/splitless inlet with pressurized liquid vaporizer

Main Findings and Discussion

The beverage CO2 method achieved reliable detection of hydrocarbons and BTEX at ppb levels and sulfur compounds plus permanent gases at low ppm, confirming its suitability for regulatory compliance. The ammonia workflow provided sharp NH3 peaks after nickel-plated lines and deactivated columns resolved peak tailing, while separate quantification of H2S ensured no interferences from salt formation.

Additional troubleshooting tips addressed peak tailing causes such as phase loss, column incompatibility, and injector dead volume, with recommended solutions including appropriate column selection, temperature control, and correct capillary installation.

Benefits and Practical Applications

• Comprehensive impurity profiling in beverage-grade CO2 to guarantee product quality and regulatory adherence.
• Accurate monitoring of ammonia breakthrough in refinery gas to safeguard downstream processes.
• Enhanced method robustness through tailored detector combinations and optimized sample introduction.

Future Trends and Potential Applications

Developments in multidimensional GC, advanced detector integration, and real-time process monitoring promise faster, more sensitive analyses. Automation of sample handling and data processing will further streamline quality control in beverage and petrochemical industries. Miniaturized GC platforms and portable detectors may enable on-site testing and rapid decision-making.

Conclusion

The tailored GC solutions detailed here deliver precise quantification of trace contaminants in CO2 and refinery gases. By combining detector selectivity with optimized columns and sampling techniques, laboratories can ensure product integrity and process safety.

Reference

No formal references provided in the source material.