Figure 1A:
MS signals (CO₂ evolution, normalized signals) during calcination of an inorganic pigment as a function of the temperature for 6 different heating rates. Experimental data are represented as symbols, solid lines represent the calculated signals. The values of the heating rate in °C/min are marked on the curves.
 

Figure 1B:
MS signals (CO₂ evolution, normalized signals) during calcination of an inorganic pigment as a function of time for 6 different heating rates. Experimental data are represented as symbols, solid lines represent the calculated signals. The values of the heating rate in °C/min are marked on the curves.

In order to apply correctly the EGA signals for the description of the kinetics of the decomposition of solids, the interaction between thermoanalytical and mass spectrometric curves in the TA-MS system has to be known [1]. If the time lag between the thermoanalytical curve (e.g. DTG) and EGA signal (e.g. MS) is negligible, the spectroscopic signal can be used not only for the qualitative analysis of the gaseous products but for the kinetic description of the process as well.

Presented examples illustrate the predicted MS curves obtained from the kinetic calculations compared to the experimental data recorded during decomposition of an inorganic pigment.

[1] B. Roduit, J. Baldyga, M. Maciejewski and A. Baiker, Influence of mass transfer on interaction between thermoanalytical and mass spectrometric curves measured in combined thermoanalyser-mass spectrometer systems, Thermochim. Acta 295, 59-71, 1997.