NUCLEAR-MAGNETIC-RESONANCE IMAGING AS A PROBE OF THE FREEZING-THAWINGPHENOMENA OF LIQUIDS IN HETEROGENEOUS SYSTEMS

NMR microscopic imaging is shown to be an excellent probe of the freez ing and thawing phenomena of liquids in heterogeneous chemical systems , and, in addition, is capable of monitoring the freezing-thawing of m ixed solvent systems. In the model mixed solvent system Me(2)SO-water, the chemical shift specific slice selective (C4S) imaging technique i s used to obtain the spatial distributions of the concentrations and m obilities of the two individual solvents in test samples. Measurements of relaxation parameters make it possible to choose values of imaging parameters TE and TR to ensure quantitative reliability of the images . Images of test samples generated at various temperatures demonstrate the qualitative relationship between image intensity and the Me(2)SO- water phase diagram. This series of experiments verifies that NMR micr oscopic imaging will be a powerful tool for the study of liquids withi n solid matrices, and in particular of cryoprotectant solvents in biol ogical systems.