THE CRYSTALLIZATION KINETICS OF GLYCINE HYDROCHLORIDE FROM FROZEN SOLUTION

Glycine hydrochloride was used as a model solute to study the quantita tive aspects of solute crystallization during the freezing process pri or to lyophilization. The kinetics of glycine hydrochloride crystalliz ation were studied between the glass transition region (-84 degrees C) and the eutectic melting temperature (-28 degrees C) by differential scanning calorimetry. Crystallization of glycine HCl proceeds via a Pr out-Tompkins model, indicating crystal growth from nuclei formed durin g the freezing process. The temperature dependence of the crystallizat ion rate constant in the temperature range studied follows Arrhenius k inetics rather than William-Landel-Ferry (WLF) kinetics.