Determination of the composition of the evolved gases is very important in thermoanalytical investigations, especially during monitoring of decomposition processes or gas-solid reactions occurring in multicomponent systems. The potential of simultaneous techniques, enabling the qualitative analysis of evolved species, such as TA-MS or TA-FTIR has been increased by introduction of PulseTA^® method [1]. Due to the possibility of injecting a known amount of any gas into the carrier gas stream, PulseTA^® provides a quantitative calibration by relating the mass spectrometric or FTIR signals to the injected quantity of probe gas.
The influence of several experimental parameters such as concentration of the analyzed species, temperature and flow rate of the carrier gas on the FTIR signals has been investigated. The reliability of quantifying FTIR signals was checked by comparison with the amount of evolved gases measured by thermogravimetry. In order to extend the opportunities of the TA-FTIR technique, possible quantification of spectroscopic signals resulting from the injection of liquids into the carrier gas stream was studied. The linear relationship between the injected amount of liquids (b.p. up to 150 °C) and the integral intensity of spectroscopic signals (peak area) also allows their quantification.

[1] M. Maciejewski, C. A. Müller, R. Tschan, W. D. Emmerich and A. Baiker, Thermochim. Acta, 295 (1997) 167.

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