DETERMINATION OF THE GLASS PROPERTIES OF D-MANNITOL USING SORBITOL ASAN IMPURITY

Due to its strong tendency to crystallize, the glass properties of man nitol cannot be measured directly. However, because mannitol can exist in a fully or partially amorphous state in drug formulations, it is i mportant to determine the glass properties of mannitol. We obtained th e glass properties of mannitol by introducing a small amount of sorbit ol, an isomer of mannitol, to delay the onset of crystallization. Extr apolation to zero sorbitol concentration yielded the following propert ies for the mannitol glass: T-g onset = 10.7 degrees C, T-g midpoint= 12.6 degrees C, T-g end = 18.4 degrees C and Delta C-p = 1.27 J/g/K. I n addition, we estimated the following parameters of the mannitol glas s from the width of glass transition using the results of Moynihan (J. Am. Ceram. Sec. 1993, 76, 1081) and Angell (J. Phys. Chem. 1994, 98, 13780). Delta H (at T-g onset) = 103 kcal/mol, D = 11, and T-0 = 222 K. The value of T-0 is consistent with the Kauzmann temperature T-K (2 36 K) obtained calorimetrically. The properties of the mannitol glass may be useful for predicting the behavior of amorphous mixtures contai ning mannitol.