Recently, PTG/e has invested in a new GC-MS and ‘Hyphenation setup’ from Perkin Elmer. With this setup, it is possible to combine the analysis techniques TGA, FT-IR and GC-MS via coupling of the devices.
The TGA-IR-GC-MS ‘Hyphenation setup’ is a powerful analysis technique to identify complex and unknown materials. Some applications for this technique are:
- The identification of additives, like plasticizers, in plastics
- Determination of the primary components of a material
- Analysis of unknown contaminations in a material, like fragrances or solvents
To characterize a material, it is first placed in the oven of the TGA, where it is heated with a programmed heating rate. During heating, weight loss can occur due to thermal decomposition or solvent evaporation. The evolved gases from these events are transferred via a transfer line to a heated chamber of the FT-IR. There, the gas is exposed to an infrared beam. The functional groups in the measured gas each respond differently to infrared radiation, which helps to identify the molecules.
Following the FT-IR, the gas is transferred via another transfer line to be injected onto the column of the GC. Depending of the affinity of the injected gas with the column, the temperature of the column and the speed of the carrier gas, the injected gas has a certain retention time. Different components have a different retention time, which enables the GC to separate the individual components of the injected gas.
An mass spectrometer (MS) is located at the end of the column. In the MS, the separated components are ionized and brought into an electric field. This field will accelerate the ionized components to a certain speed, depending on their mass and charge. The MS uses this principle to create a spectrum, which, together with the retention time of the GC, is unique for each component. Combining the data from FT-IR and GC-MS, the individual components of the evolved gases from TGA can be characterized.
Aside from the fully hyphenated setup, it is also possible to use the individual analysis techniques, or a partially hyphenated setup, for example TGA – IR or TGA – GC-MS. The specific required setup will depend on what needs to be analyzed exactly.
Perkin Elmer equipment:
Clarus 690 GC & SQ8T MS