Ion-interaction chromatography of several metallocyanide complexes stabilized by adding cyanide in a neutral mobile phase

Standard solutions (at 10–5 M levels) of Cu(I)- and Fe(II)-cyanide complexes were stabilized for at least 5 h using 0.5 mM cyanide solution (around pH 9) as a medium. Complexes of Cu(I)- and Fe(III)-cyanide also could be stabilized without any dissociation by adding 1 mM cyanide to an acetonitrile–water (18:82, v/v) mobile phase (pH 7.0) containing 10 mM tetra-n-propylammonium salt (TPA). Under the optimal conditions, the six complexes of Cu(I)-, Ag(I)-, Ni(II)-, Fe(II)-, Fe(III)- and Au(I)-cyanides were resolved from their mixtures within about 45 min, with well-shaped chromatographic peaks