Evolved gas analysis. What about quantification? Focus on the couplings between thermogravimetry and gas chromatography mass spectrometry
Résumé
Coupling TGA to MS, FTIR, GC-MS, or μGC-MS instruments clearly enhances the basic information given by TGA alone.
The composition of emitted gases obtained by evolved gas analysis (EGA) provides an in-depth look at the mechanisms of decomposition/degradation of materials as well as information on the toxicity of the material during heating. EGA also allows de-formulating a material to understand its physico-chemical behavior under heating.
The couplings mentioned above are powerful techniques that yield both quantitative (mass loss) and qualitative (identification) information about the gaseous products released during a TGA measurement. Each coupling has its own specificity. Interpretation of infrared spectra or mass spectra becomes more complicated when many unknown gases are simultaneously released. In this case, a separation step becomes necessary.
An interesting coupling such as TGA-Storage interface-GC-MS can be used for the analysis of complex gaseous mixtures coming from plastics, bitumen, resins, silicones, waxes, etc. Another coupling allowing separation of small molecules such as permanent gases, light solvents, light and medium VOC could be the TGA-μGC-MS. With these two couplings, the emitted gases will not only be separated and identified, but also quantified by using different methods of quantification and this will be shown through several examples of applications.