Glycerol as a Cryoprotectant: An Undergraduate Experiment Using Differential Scanning Calorimetry to Study Glycerol–Water Mixtures

This study describes a laboratory experiment performed with undergraduate physical chemistry students utilizing differential scanning calorimetry (DSC) to determine a eutectic phase diagram, measure solution glass transition temperatures (Tg), and predict the glass transition temperature (T_g) of water. The DSC techniques employed determine accurate equilibrium freezing temperatures (Tf) of glycerol–water mixtures with glycerol mole fractions (x_g) between 0 and 0.201. When x_g ≥ 0.300, the slow rate of crystallization of glycerol inhibits crystallization, and solutions exhibit a T_g rather than a T_f. The T_f’s serve to discuss solid–liquid equilibria and estimate eutectic phase diagrams with varying levels of accuracy. The T_g’s serve to estimate the T_g of water (135.3 ± 1.2 K). Together, these behaviors allow for discussion of glycerol’s effectiveness as a cryoprotectant.

Reference

Alexander D. Schwab, J. Chem. Educ., 2024, 101 (4), 1696-1702, 10.1021/acs.jchemed.4c00102