Modes for Pyrolysis
Gases evolved during programmed heating of a sample are directly transferred into MS to monitor temperature profile of volatile sample components.
Therefore pyrolyzer and MS detector are combined with a short deactivated EGA capillary. During the GC oven is held constant at 300 °C, the pyrolyzer is heated by a temperature program from 40 to 500 °C.
This pyrolysis mode requires the Multi-Shot Pyrolyzer.
The Single-Shot GC/MS is also called flash, filament or curie-point pyrolysis.
This term is used to describe the pyrolysis of a sample at a fixed temperature. The pyrolysate is separated and detected in the gaschromatograph. The simultaneous dissolution of all sample compounds reuslt in pyrograms containing information about numerous compounds. The analysis of complex samples can be difficult because of peak overlap and defective data evaluation.
Therefore the Double-Shot technique should be used for the analysis of cmplex samples.
Double-Shot is a process of performing two GC analyses on one single sample.
First: The volatile fraction of the sample is thermally desorbed (pyrolyzer furnace is heated by a temperature program, e.g. 80 °C to 350 °C at 15 °C/min), chromatographically separated and finally detected. Then the sample is re-located to a region at ambient temperature.
Second: After the completion of the GC analysis of the volatile fraction, the sample is again dropped into the furnace (niw set to the pyrolysis temperature) and pyrolyzed providing the information of its polymeric fraction.
This pyrolysis mode requires the Multi-Shot Pyrolyzer and the MicroJet Cryo-Trap.
HC-GC/MS utilizes the EGA thermogram to define thermal zones of evolving compounds. Each zone can be sampled independently using the MicroJet Cryo-Trap and the Selective Sampler.
The analysis of each thermal zone yields a chromatogram containing only those compounds evolving from the sample of the selected temperature range. So you require detailed information about the composition of the sample.
This mode for pyrolysis requires the Multi-Shot Pyrolyzer, the Selective Sampler and the MicroJet Cryo-Trap.
Reactive pyrolysis is a method, that is used for complete characterization of complex matrixes or to avoid extensive sample preparation
It is possible, that degradation products prohibit the detection of given target compounds. When the target compounds can be derivatized, the derivatives can be detected and quantitated. Time-consuming sample preparation can be replaced by reactive pyrolysis. The untreated sample is placed in the sample cup, the reagent is added and the sample is ready for analysis. Using the Auto-Shot Sampler, this process can be fully automated.
For optimizing reactive pyrolysis, the Auto-Rx Disc and the Micro-Reaction Sampler can be used.