In order to correctly design the storage of nuclear wastes in nuclear glasses it is necessary to characterize the mechanisms of migration of silicon especially in the gel layer which forms at the glass/environment interface. Among the different available techniques, the chromatography theory coupled with the systemic approach developed by Villermaux and coworkers is particularly indicated when dealing with trace level ion-exchange processes. This paper illustrates the advantages and limitations of this methodology through the study of Na-23/Na-22 isotopic exchange and Na-23/H ion-exchange processes. Despite the fact that the coefficient of ionic diffusion is determined with a worse accuracy than with the classical "through diffusion" technique, the interest of such a methodology lies not only in the richness of the collected information on the underlying processes occurring in the migration of the studied species, but also in the easiness and rapidity of related experiments.