The ’H NMR Relaxation of Water in Avian Eggs
Eggs were used as subjects during early developments of NMR imaging because they were of a size convenient for the existing magnets and because the development of the embryo in the fertilised egg provided an interesting system for study. As the image depended upon the relaxation properties of the different constituents parallel relaxation studies were undertaken to monitor changes in relaxation as functions of size and of age under different storage conditions. Eggs were collected, labelled, weighed and stored, at 6°C and low relative humidity, or at 36°C and 80% relative humidity to simulate incubation conditions. After an appropriate storage period the eggs were reweighed and the weight loss determined, broken open and four parts dissected out, the yolk, the thin and the thick white albumens and the chalazae. These were loaded into NMR sample tubes and various measurements undertaken. The reduction in weight during the ageing process is usually ascribed to a loss of water, mostly from the albumens, by evaporation through the shell. There may be an additional re-distribution of water between the albumen and yolk. As the NMR spectrometer was normally arranged to detect the slower relaxing 'H components attributed to water, NMR relaxation should provide a reasonable mechanism for monitoring the water distribution and relaxation and implicitly motional properties. The rate of fractional weight loss was dependent upon storage condition and thermal history.
KeywordsRelaxation Rate Spin Lattice Relaxation Relaxation Data Spin Lattice Relaxation Time Free Water Content
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- 4.A.L. Romanoff and A.J. Romanoff, The Avian Egg. Wiley, New York (1949).Google Scholar