Selection of Additives for the Characterization of Enantiotropic Polymorphs of Organic Crystals by Eutectic Melting

Polymorphs can be characterized by the use of eutectic melting point data, which permits the determination of both the thermodynamic stability relationships for anhydrous polymorphic systems and the transition temperature for enantiotropic polymorphs. This technique requires the selection of suitable additives to produce eutectic mixtures. However, there is very limited information in the literature about how these additives should be selected. This gap is addressed herein through the study of the reported additives and their physical properties. A set of additives with wide applicability is recommended, and guidance on the selection process is presented.