SEPARATION OF METALLO-CYANIDE COMPLEXES BY CAPILLARY ZONE ELECTROPHORESIS

The optimisation of electrolyte systems for the separation and detection of cyanide complexes of Au, Pt, Fe(II), Fe(III), Pd, Cu(I), Co, Ag, Cr and Ni using capillary zone electrophoresis is described. A phosphate-triethanolamine buffer at pH 8.5 was chosen for the separation. The factors affecting resolution and analysis time include the addition of ion-pairing reagents (which also act as electroosmotic mobility modifiers) as well as organic solvents to the carrier electrolyte. Less stable cyano complexes [such as those of copper(I)] require the presence of low concentrations of free cyanide in the electrolyte in order to achieve acceptable peak shapes. Direct UV detection at 214 nm is feasible for most of the metallo-cyanide complexes although some of them giver higher response in an indirect mode at 254 nm using trimellitate as the carrier electrolyte. Approaches for preconcentration are discussed in order to achieve detection limits necessary for environmental samples and other applications.