Autori: BOGDAN TITA, ADRIANA FULIAS, MIRCEA STEFANESCU, ELEONORA MARIAN, DUMITRU TITA

Editorial: Revista de Chimie, 62(1), p.31-36, 2011.

Rezumat:

The application of thermal methods is of great importance regarding the pharmaceutical problems such as
the control of raw materials, the determination of purity, the qualitative and quantitative analysis of drug
formulation, tests of thermal stability and compatibility, the determination of kinetic parameters etc. The
purpose of a kinetic investigation is to calculate the kinetic parameters and kinetic model for the studied
process. The results are further used to predict the system behaviour in various circumstances. A kinetic
study regarding the sodium diclofenac thermal decomposition was performed under isothermal conditions
in a nitrogen atmosphere, the temperature having the following values: 280, 285, 290, 295, 300°C. The TG/
DTG data were processed by three methods: isothermal model-fitting, isothermal-isoconversional and
Friedman’s isothermal-isoconversional. The model-fitting defines a single reaction step, while the model–
free approach represented by isothermal-isoconversional methods gave dependences of the activation energy,
of the extent of conversion. The obtained results are in good accord with the similar data which resulted in
non-isothermal conditions from a previous work. The careful treatment of the kinetic parameters obtained
under different thermal conditions was confirmed as necessary, as well as a different strategy of experimental
data processing.

Cuvinte cheie: sodium diclofenac, thermal analysis, TG/DTG/DTA, kinetic study