Impregnation of silica gel with inorganic salts from the standpoint of specific adsorption theory. The effect of this impregnation on the separation of sugars by TLC

Results from the separation of some neutral sugars on silica gel plates imp regnated with sulfates, chlorides, and nitrates of various metals are prese nted. The effect of pH and of the concentration of the impregnating solutio ns has been studied, It is shown that impregnation with sulfates, in contra st to nitrates and chlorides, leads to decreasing R-F values and to improve d separation selectivity, For the sulfates the effect of the nature of the cation on R-F increases in the order: K+ < Na+ < Ni2+ < Co2+ < Mg2+ < Cu2< Zn2+ < Mn2+. Attempts are made to explain these results in terms of moder n concepts of electrolyte behavior in solutions, the state of the silica ge l surface, and specific cation adsorption from solutions on to the surface of solid oxides. The behavior of anions as ligands in solution and in the s urface complex is considered.