Experiments to separate copper, nickel, zinc and cobalt were carried out on an unmodified Vycor porous glass-packed column using pyridine-2,6-dicarboxylic acid (PDCA) as all eluent. The retention Volumes of zinc and cobalt had the maximal values around pH 3, because the concentrations of hydrogen ion and PDCA anion are both low. Copper, nickel and zinc were eluted in order with a large stability constant of PDCA complex which included these metals as a central metal. On the other hand, cobalt was elated the last without following this rule. It was considered that cobalt ion was oxidized to change into the trivalent cation in the column. These four metals were completely separated in 150 min under the conditions of eluent pH of 3.0, PDCA concentration of 0.05 mol/m(3) and column length of 150 mm; and in 60 min under the conditions of eluent pH of 2.5. PDCA concentration of 0.15 mol/m(3) and column length of 300 mm. Thus it was shown that an unmodified Vycor porous glass-packed column Could be used to separate divalent transition metals.