Differential Scanning Calorimetry

Differential scanning calorimetry (DSC) is a analytical technique in which the difference in the amount of heat required to increase the temperature of a sample and a reference is measured as a function of the temperature. The basic principle underlying this technique is that when the sample undergoes a physical transformation, such as phase transitions, more or less heat will need to flow to it than to the reference, in order to maintain both at the same temperature. Therefore, by observing the difference in heat flow between the sample and the reference, differential scanning calorimeters are able to detect physical transformations and to measure the amount of heat absorbed or released during such transformations.

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This work focused on the development of innovative methods, based on enthalpy balances and Differential Scanning Calorimetry (DSC), for the estimation of the thermal properties of polymorphic pharmaceutical compounds. A first method was developed to determine the melting enthalpy of crystalline compounds which are metastable near their melting temperature. A second method was developed for the determination of the solid–solid transition temperature separating the temperature ranges of stability of two crystallographic forms. A third method was developed in order to construct liquid-solid phase diagrams. These three methods were applied to the enantiotropic system of Etiracetam, and both of its two crystallographic forms so far identified.

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Differential Scanning Calorimetry (DSC) is used for the characterization of small solid polymer taht are formed during the elimination of Bisphenol A (BPA) from water using laccases oxidative enzymes. In this process, BPA is transformed by the laccase in polymers that precipitate and can be filtered. The process parameters have an important impact on the polymerization kinetics and lead to different polymers. Characterizing these polymers is thus important to enhance the understanding of the treatment that is used. The size of the polymeric chains can be estimated knowing the thermal properties that can be evaluated using the DSC: glass transition temperature and change in specific heat after this transition.