Da. Orlovich et Ae. Ashford, X-RAY-MICROANALYSIS OF ION DISTRIBUTION IN FROZEN SALT DEXTRAN DROPLETS AFTER FREEZE-SUBSTITUTION AND EMBEDDING IN ANHYDROUS CONDITIONS, Journal of Microscopy, 180, 1995, pp. 117-126
A model system using dextran droplets of different salt solutions eith
er frozen together, or sandwiched together after freezing and then fre
eze-substituted, embedded and dry sectioned has been investigated by X
-ray microanalysis, X-ray maps and spot measurements taken in transect
s through the interface of both droplets have shown that the P, K and
Ca remain well localized in their original droplet, This validates fre
eze-substitution as a method for localization of these elements in bio
logical samples, Results with Na were more variable and not always exp
lainable. Success was achieved by the use of super-dry solvents and ma
intenance of a dry environment at all stages. We emphasize the need to
avoid water contamination not only during freeze-substitution but als
o during sectioning, storage and section transfer to the electron micr
oscope.