COMPOSITION OF CRYSTALLITES RESULTED FROM FREEZING OF WATER SOLUTIONS OF BIOMOLECULES AT CRYOGENIC TEMPERATURES. Kosevich M.V., Shelkovsky V.S., Boryak O.A., Stepanov I.O.; Institute for Low Temperature and Engineering NAS Ukraine, Kharkov, Ukraine.

Chemical composition of the micro crystallites formed due to phase separation of the multi-component water solutions of biomolecules and inorganic compounds during freezing can be directly determined by the recently proposed method of the low temperature fast atom bombardment (FAB) mass spectrometry. It was observed, that in addition to powerful analytical potential, FAB mass spectrometry appeared to be extremely sensitive to the energetic and structural parameters of the frozen solutions at the cryogenic temperatures. The patterns of the clusters sputtered from the frozen solid, reflects the nano-scale arrangement of molecules and ions in crystal and glassy phases. The hydrate clusters (H₂O)n*M are recorded only for crystalline hydrates and compounds with strongly bound water. Phase transitions in the samples with temperature change (dehydration of crystalline hydrates, sublimation, glass-crystal transitions) are clearly reflected in the changes in mass spectral pattern. The possibility of the study of phase composition and transitions in the frozen solutions, which contain cryoprotectors and biomolecules, are of exceptional value for cryobiology. The formation of complexes of biomolecules in the frozen solid, prohibited in solutions, is also elucidated from the corresponding clusters. The design of the dedicated cryogenic block for the secondary emission FAB ion source of a magnetic mass spectrometer, which allows to control the sample temperature in the 77-3OOK range, is described.