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Autori: BOGDAN TITA, ADRIANA FULIAS, MIRCEA STEFÃNESCU, ELEONORA MARIAN, DUMITRU TITA
Editorial: Revista de Chimie, 62(2), p.216-221, 2011.
Thermal analysis is one of the most widely used methods for studying the solid state of pharmaceutical
substances. The thermoanalytical curves provide important information regarding the physical properties of
the pharmaceutical compounds (stability, compatibility, polymorphism, phase transition, kinetic analysis
etc). The purpose of a kinetic investigation is to calculate the kinetic parameters and the kinetic model for the
studied process. The results are further to predict the system behaviour in various circumstances. This paper
is the third one of a systematic study regarding the thermal behaviour of ibuprofen and its compatibility with
excipients. Simultaneous thermogravimetry/derivative thermogravimetry (TG/DTG) and differential thermal
analysis (DTA) techniques were used for the characterization of the thermal decomposition of ibuprofen.
Thermal curves revealed that the thermal decomposition occurs in one step, after melting, in the temperature
range of 180–300°C and in a nitrogen atmosphere. A kinetic study regarding the ibuprofen thermal
decomposition was performed under isothermal conditions for the temperature steps: 190; 195; 200; 205;
210°C. The TG/DTG data were processed by three methods for decomposition process following first order
reaction: isothermal model-fitting, isothermal-isoconversional and Friedman’s isothermal-isoconversional.
The obtained results are in accord with the data resulted in non-isothermal conditions from a previous work.
The careful treatment of the kinetic parameters obtained in different thermal conditions is necessary, as
well as the choice of the adequate calculation method.
Cuvinte cheie: ibuprofen, TG/DTG/DSC, isothermal, non-isothermal, thermal decomposition,kinetic study