Thermal Desorption

Thermal Desorption (TD)
The detailed analysis of a complex material is a challenging task. It may be necessary to detect and quantitate a full spectrum of residual solvents, monomers and oligomers, in addition to a vast number of possible additives. In order to fully characterize the material of interest, a variety of sample preparation regimes (e.g., Soxhlet extraction, derivatization, etc.) are utilized to isolate the target compounds from the sample matrix. While these techniques do serve to remove most of the potential interference, they are often complicated, time consuming and invariably adversely affect data quality.
The Frontier multi-functional pyrolyzer utilizes a temperature programmable furnace. The sample can be “injected” at a relatively low temperature (ca. 40°C) and heated to a high temperature (ca. 700°C). As the sample temperature increases, individual sample constituents evolve from the sample and are carried to the splitter and ultimately to the detector. A plot of sample temperature versus detector response is called an EGA thermogram. The thermogram profile defines the thermal zone over which a given compound evolves from the sample.
Thermal desorption is simply a technique for analyzing the constituents evolving from the sample over a given temperature range see zone A (150->270°C) in the EGA thermogram above. Using heat to desorb a group of sample constituents greatly simplifies the analytical protocol. There is no sample preparation step, per se’ the sample is analyzed as is. The resulting chromatograms are generally quite simple only the compounds evolving from the sample over the pre-selected temperature range are separated on the GC column. The higher boiling fraction of the sample remains in the sample cup. If necessary, it can be examined after the GC analysis of the compounds thermally desorbed is complete.
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