Effect of cryoprotectants on eutectics of NaCl·2H2O/ice and KCl/ice studied by temperature wave analysis and differential scanning calorimetry

The effect of cryoprotectants (sucrose, glucose, dimethyl sulfoxide (DMSO) and polyvinylpyrrolidone (PVP)) on the eutectics of NaCl·2H2O/ice and KCl/ice have been studied by temperature wave analysis (TWA) and differential scanning calorimetry (DSC). The eutectic crystallization was inhibited by the cryoprotectant, and a higher inhibitory ability was observed in NaCl systems (water/NaCl/cryoprotectant) than in KCl systems (water/KCl/cryoprotectant) with the same additive concentration. In the above system, sugars showed the higher inhibition ability than DMSO or PVP. The increase of thermal diffusivity with the increasing sugar concentration at a temperature immediately after the eutectic melting in KCl/sugar systems suggested a characteristic hydration of sugar and K+ ion, this was not observed in NaCl/sugar systems.