Evolved Gas Analysis (EGA)
All TGA and TGA/DSC as well the TMA840 and TMA/SDTA versions can be connected online to a mass spectrometer (MS), an FTIR spectrometer or to a GC/MS system. Analysis of the decomposition products yields additional information about the sample. This enables you to interpret measurement curves with greater certainty.
- TGA-MS: High sensitivity – Extremely small amounts
of substances can be detected
- TGA-FTIR: High chemical specificity – Ideal for sub-
stances that exhibit medium to strong IR absorption
- TGA-GC/MS: High sensitivity – Best separation
specific detection of smallest amounts
The TGA is coupled to the MS via a fused silica capillary tube heated at 200 °C to prevent condensation. Part of the gases evolved from the sample in the TGA is sucked into the MS. In order to be able to connect the TGA-MS interface is needed.
TGA-FTIR combination uses the total volume of purge gas and gaseous decomposition products from the TGA. The gases are transferred through a heated glass-coated steel transfer capillary line into a heated gas cell in the FTIR spectrometer. In order to be able to connect the TGA-FTIR interface is needed.
The TGA-IST16-GC/MS system is the ideal solution for the comprehensive qualitative and quantitative molecular analysis of gaseous decomposition products.
Residual solvents in pharmaceutical substances
Many pharmaceutical substances are recrystallized from solvents. As a result, residues of solvents often remain in the product. Combined techniques such as TGA-MS are ideal to detect and identify such undesired residues. In the example, methanol and acetone were used to recrystallize the active substance. The presence of these two substances is confirmed by the peaks in the m/z 43 and m/z 31 fragment ion curves. The results indicate that the weight loss step at 200 °C is almost entirely due to the elimination of acetone.
Thermal behavior of cable insulation material
TGA-FTIR analysis was used to determine whether corrosive substances are formed in the processing of ETFE cable insulation material for metal connections during thermal treatment. The analysis of finished insulation material indicated that the sample released volatile substances at temperatures above about 275 °C. An IR spectrum recorded during the main decomposition process at 510 °C shows that alkyl fluorides and hydrogen fluoride (HF, 3500—4000 cm-1) are produced as decomposition products. HF is therefore released at high temperatures and could potentially attack metal connections. The use of ETFE is, however, perfectly acceptable because processing is performed at lower temperatures.
Delamination of printed circuit boards
Using TMA as a very sensitive method the temperature of the first irreversible change (delamination) can be determined and at the same time the nature of the gases evolved can be identified.