High-Sensitivity Analysis of Impurities in Gas (1)

Importance of the Topic

The purity of industrial, medical and food grade gases is essential to maintain product quality, ensure human safety and comply with regulatory requirements. Sensitive detection of trace level impurities supports reliable quality control and minimizes risks associated with harmful contaminants.

Objectives and Overview

This study demonstrates the application of the Shimadzu Tracera high sensitivity gas chromatograph equipped with a barrier discharge ionization detector for simultaneous analysis of inorganic gases and lower hydrocarbons. Impurity profiling was performed on ethylene feedstock and carbon dioxide intended for use as a food additive to assess performance against established quality standards.

Methodology and Instrumentation

The analysis combined the following instrument configuration and chromatographic conditions

• Gas Chromatograph Tracera (GC-2010 Plus A with BID-2010 Plus detector)
• Manual gas sampler MGS-2010 with helium purge to minimize ambient air contamination
• GCsolution software for data acquisition
• Micropacked ST column with temperature program: initial 35 C for 2.5 min, ramp 20 C/min to 250 C (0 min), ramp 15 C/min to 270 C (5.42 min); total run time 20 min
• Carrier gas helium; pressure program from 250 kPa (2.5 min) increasing at 15 kPa/min to 400 kPa (7.5 min)
• Injection split ratio 1:5, injection port 150 C, detector 280 C, discharge gas helium at 70 mL/min, injection volume 1 mL

Results and Discussion

Impurity analysis of ethylene revealed the presence of hydrogen (30 ppm), carbon monoxide (2 ppm), carbon dioxide (15 ppm) and methane (30 ppm). For carbon dioxide used as a food additive, trace methane (2.2 ppm) and ethylene (1.5 ppm) were detected. The barrier discharge ionization detector provided stable baseline correction and achieved detection limits in the low ppm range for both inorganic and hydrocarbon species.

Benefits and Practical Applications

Implementing the described method allows laboratories to perform comprehensive quality assurance of specialty gases with a single analytical platform. The use of a helium-purged sampler reduces the risk of ambient air intrusion, enhancing the reliability of O2 and N2 quantification. This approach supports compliance with food safety regulations and industrial specifications.

Future Trends and Possibilities

Advancements may include automated sample introduction, coupling with mass spectrometric or chemiluminescence detectors for enhanced specificity, and integration of multidimensional separations. Portable high-sensitivity GC systems and data analytics driven quality control are emerging areas that could further streamline impurity monitoring.

Conclusion

The Shimadzu Tracera GC with barrier discharge ionization detection demonstrates robust performance for simultaneous high-sensitivity analysis of both inorganic gases and hydrocarbons. This method provides a reliable tool for monitoring trace impurities, ensuring gas quality across diverse applications.

References

• Shimadzu Corporation LAAN J GC E010 High Sensitivity Analysis of Impurities in Gas First Edition July 2013