Stripping-like phenomenon of metal dithizonates in gel chromatography

Dithizonates of some metals, Zn(II), Cd(II), Pb(II), Hg(II), Bi(III), Co(II) and Cu(II) were chromatographed on Sephadex LH-20 gel column using carbon tetrachloride as an eluent. Among them, the metal ions of Zn, Cd, Pb, Hg and Bi were adsorbed at the top of the column, and the liberated dithizone was easily eluted out of the column, while dithizonates of Co and Cu were eluted out unchanged. These phenomena are very curious but somewhat analogous to the stripping procedure in the solvent extraction process. The mechanism of this ''stripping-like phenomenon'' seems to be difficult to elucidate but it can be conveniently applied to the purification of dithizone reagent as well as to separate some metal dithizonates. (auth.)