Introduction

Nitrous Oxide (N2O), Carbon Dioxide (CO) and Methane (CH4) are considered to be very powerful greenhouse gases. These gases reflect in the atmosphere, stopping the incoming and outgoing radiation that warms the Earth, thus causing the greenhouse effect. Continuously measuring the greenhouse gases gives insight into the source of the emissions, helping us fight climate change. A SCION 8500 GC was custom configured specifically for the analysis for all three gases in a single matrix of atmospheric air containing water vapour.

Experimental

A SCION 8500 GC was equipped with a gas syringe, PWOC 1041 injector, TCD, ECD and FID detectors. Two channels are used with one equipped to two detectors. After injection on the first channel, CO2 and CH4 are separated from the air. The TCD detects the CO2, configured in series with the TCD, detects the CH4. The ECD, on the second channel, detects the N2O once separated from the water. The water is backflushed to vent. Figure 1 shows a schematic drawing of the greenhouse gas analyser.

Four columns are required for the analysis; all being 1/8th inch stainless steel packed columns. Two of the columns were used for the pre-separation of the compounds from the matrix and the final two for the complete separation of compounds. Table 1 shows the role of the columns used within this application.

Figure 1. Schematic configuration of the greenhouse gas analyser

Table 1. Analytical requirements of the four columns

Table 2 shows the analytical parameters for the greenhouse gas analyser.

RESULTS

The configuration of the analyser allows three simultaneous chromatograms to be obtained. Figure 2 shows the TCD channel chromatogram where CO2 is analysed. CH4 is analysed on the FID channel, as shown in Figure 3. Figure 4 shows N2O when analysed on the ECD channel.

Figure 2. Separation of 1000ppm CO2 from O2 and N2.

Figure 3. Separation of 5ppm CH4 from O2 and N2

Figure 4. Separation of 1ppm N2O from bulk O2

The system suitability and repeatability were tested through a test sample being analysed with ten replicates. Table 3 details the repeatability data. The repeatability data was excellent with an RSD below 2% for all analytes.

Table 3. Repeatability data on peak area

The configuration of the analyser also allows for expansion of N2O to CFC’s and SF6. Figure 5 shows the extended ECD channel for SF6 analysis.

Figure 5. Separation of 1ppb SF6 from N20

Conclusion

A SCION 8500GC was configured as a greenhouse gas analyser for the analysis of carbon dioxide, methane and nitrous oxide in a single run. Repeatability data was excellent showing that the system is perfectly suites for the analysis of greenhouse gases. This system is highly flexible with the application range easily expanded to cover CFC’s and SF6.

Download Application Note

Download the complete Application Note: Analysis of Greenhouse Gases by Gas Chromatography

SCION Gas Chromatography Analyser

A SCION Gas Chromatography Analyser was used to conduct this research.

If you would like to speak to a member of our team for more information, please don’t hesitate to get in touch.