Pyrolysis Double-Shot

The term “Double-Shot” is becoming common-place in the world of material characterization. However, there appears to be some confusion on the exact meaning of the term “Double-Shot”.” In its original form, Double-Shot describes the process of performing two analyses on a single sample. First, the volatile fraction of the sample (i.e., residual solvents, chemical additives, monomers, oligomers, etc.) is thermally desorbed, chromatographically separated and finally detected. Once the volatile fraction has been desorbed, the remaining fraction of the sample is re-located to a region at ambient temperature. This prevents sample degradation during the chromatographic analysis of the desorbed volatile fraction.
When the analysis of the volatile fraction is complete, the GC oven temperature is reset to initial temperature and the pyrolyzer furnace is set to the “Pyrolysis” temperature. The sample is rapidly dropped into the furnace where flash pyrolysis occurs; the pyrolyzates are transported to the analytical column and the oven temperature program commences.
Here is a typical furnace program for a classic “Double-Shot” analysis:
First Shot 80 –> 350℃ at 15℃/min
Second Shot 550℃
The first shot produces a total ion chromatogram (if using a GC/MS) of the volatile fraction of the sample.
The second shot produces a pyrogram of the polymeric fraction of the sample.
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