Evolved Gas Analysis (EGA)

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The first step when developing a method using the Frontier multi-functional pyrolyzer is to perform an Evolved Gas Analysis (EGA); the sample is dropped into the furnace which is at a relatively low temperature (ca. 40-100℃). The furnace is then programmed to a much higher temperature (ca. 600-800℃). Compounds “evolve” from the sample as the temperature increases. A plot of detector response versus furnace temperature is obtained. The example below contains two EGA thermal zones. Furnace Temperature .

The EGA provides a clear picture of the sample complexity and, by using extracted ion chromatograms (GC/MS) or appropriate standards (FID, etc.), one can identify the EGA thermal zone where specific compounds of interest evolve from the sample. The EGA is used to determine the next step in the evolution of the analytical method. In the figure above, one can learn about the ‘volatiles’ in the sample by simply introducing the sample at 300℃ only the compounds evolving below 300℃ will evolve from the sample and be transported to the head of the column and analyzed. 

If there is interest in both the ‘volatile’ and the higher boiling fractions, it may be necessary to add a Microjet-Cryo Trap. The Microjet-Cryo Trap re-focuses the analytes of interest at the head of the column so that the full separating power of the column can be utilized.