Coupling of chromatographic ion-exchange reaction with change-partner reaction: Presumed mechanism on the ion–ion interaction of inorganic ions in Sephadex G-15 columns

A sample solution containing sodium or potassium dihydrogenphosphate or disodium or dipotassium hydrogenphosphate was eluted from a Sephadex G-15 column with either sodium or potassium chloride solution in various sample–eluent systems, and every one of the four kinds of ions employed was determined in the eluate. Then, the elution profiles showed the phenomenon that a negative peak of chloride ion coexisted in the fractions of a positive peak of phosphate ion, in all sample–eluent systems employed. This phenomenon was assumed to occur by the coupled reaction of change-partner and ion-exchange reactions including ion exclusion.