SEPARATION AND DETERMINATION OF DIVALENT METAL IONS WITH UV-ABSORBING CHELATING AGENTS BY CAPILLARY ELECTROPHORESIS

Abstract

Capillary electrophoresis separation of several divalent metal ions, as well as iron(III) and silver(I) was examined with chelating agents. The metal chelates separated in the capillary were measured by on-column UV-absorption detection. When 1, 2-cyclohexanediamine-N, N, N' N'-tetraacetic acid(CyDTA) was used as an chelating agent in a carrier solution (pH 9) the order of the migration time (tm) of metal ions was as follows: Ba²⁺ <Sr²⁺<Ca²⁺<Mg²⁺(Be²⁺ could not be detected), Fe³⁺<Mn²⁺<Co²⁺(Ni²⁺<Cu²⁺>Zn²⁺) and Cd²⁺<Pd²⁺< Ag⁺, Hg²⁺<Pb²⁺ The detection limits of common metal ions were 10^-6M, when CyDTA chelates were used. The method with CyDTA was applied to the determination of Ca²⁺ and Mg²⁺ in water samples: the separation and detection of Ca²⁺ and Mg²⁺ was carried out within 10min, and the relative standard deviations for around 10^-4M metal ions was less than 1.5%.