EFFECT OF CRYOPROTECTANTS ON THE EUTECTIC CRYSTALLIZATION OF NACL IN FROZEN-SOLUTIONS STUDIED BY DIFFERENTIAL SCANNING CALORIMETRY (DSC) AND BROAD-LINE PULSED NMR

The effects of cryoprotectants (sugars and polymers) on the eutectic c rystallization of NaCl/water systems were studied by differential scan ning calorimetry (DSC) and broad-line pulsed NMR. Thermal analysis of frozen NaCl solutions showed a melting peak of eutectic NaCl/water sys tems at around -21 degrees C. The addition of various cryoprotectants inhibited the eutectic crystallization of the NaCl solution. The conce ntrations of polymers (dextran, polyvinylpyrrolidone and Ficoll) requi red to inhibit eutectic crystallization were slightly higher than thos e of sugars (glucose, sucrose, trehalose and lactose). The proportions of liquid-phase protons present in frozen H2O and D2O solutions, dete rmined by broad-line pulsed NMR, showed that the addition of sugar inh ibits eutectic crystallization of NaCl/water systems through the forma tion of an amorphous mixture containing NaCl, sugar and water between the ice crystals.