Estimation Of Temperature Dependency On Crystallization Using The Critical Supersaturation Ratio (Sc)

In order to obtain high quality crystals, the cooling rate and crystallization temperature are usually adjusted in the manufacturing process. In this study, the temperature dependency of the crystallization process was evaluated using theophylline, noscapine and clotrimazole. The crystallization temperature of theophylline at several concentrations was affected by the cooling rate. With lower concentration, the crystallization temperature decreased, especially at higher cooling rates. In our previous study, the critical supersaturation ratio (Sc) was defined as an index to estimate degree of crystallization difficulty. The Sc of theophylline, noscapine and clotrimazole in several crystallization solvents showed a clear difference around 273 K, but converge to less than 1.0 around 333 K. These results indicate that a higher temperature condition can decrease the Sc value, especially for a compound having a large Sc. Thus, using a high temperature condition could be recommended to crystallize a compound which is difficult to crystallize at room temperature.