Separation of Polymorphic Forms by DSC

摘要

Differential scanning calorimetry (DSC) provides insights into phase transitions, forrnexample melting, crystallization and solid-solid transitions,. Very important is the knowledge ofrnthe polymorphic forms of drug substances due to the fact that the bio-availability and stabilityrndepends strongly on the crystal form. Therefore, DSC is an ideal tool to investigate the transitionsrnof the polymorphs. In addition to this analysis, DSC can be used to create different modificationsrnby cooling the melt at different rates. During the subsequent heating the materials mayrnrecrystallize to other forms. Thus, the variation of the cooling and heating programs is used tornfind and separate polymorphic crystal forms. Simultaneous visual observation helps to interpretrnthe DSC curves and to identify the transitions. In addition to these investigations, DSC allows torndetermine the purity and its changes of it by repeated measurements. This may indicate decompositionrnreactions during the measurement of polymorphism. Important decomposition reactionsrnare directly visible on the DSC curve.