Volume 26, Number 5, June 1998Microcolumn separation techniques developing in Japan
|198 - 204
Polymorphism of sugars studied by time domain NMRD. Le Botlan, F. Casseron and F. Lantier
Laboratoire d'Analyse Isotopique et Électrochimique de Métabolismes, UPRESA CNRS Q6006, Faculté des Sciences, BP. 92208, 44322 Nantes Cedex 03, France
The T1 NMR relaxation time measured by time domain NMR spectroscopy was used to compare the mobility of the solid state of different sugars. To avoid time consuming experiments, a relaxation delay inferior to 5. T1 has been used for crystalline samples. In this case, the commonly used relationship can no longer be used. The analysis of relaxation curves by a continuous method (CONTIN program) allowed to obtain quantitative results for crystalline and amorphous phases in mixtures, well related to experimental values. Photos by electronic scanning microscopy of crushed crystalline sucrose show pieces of sucrose with rounded corners, probably due to a partial melting of sucrose during crushing. This layer must be in an amorphous state. However, X-ray diffraction spectra did not show a significant amount of an amorphous phase. The very slight difference in the position of the T1 distribution between rough crystalline sucrose and crushed sucrose could be due to the occurrence of an amorphous phase at the surface of the crystals.
Key words: Time domain NMR / T1 relaxation time / sugars / amorphous phase.
© EDP Sciences, Wiley-VCH 1998