Separation of uranium(VI) and transition metal ions with 4-(2-thiazolylazo)resorcinol by capillary electrophoresis

A capillary electrophoresis method utilizing 4-(2-thiazolylazo)resorcinol (TAR) was developed to separate uranium, cobalt, cadmium, nickel, titanium and copper metal ions. TAR was chosen as the visible absorbing chelating ligand because of its ability to form stable complexes with a wide variety of metals. Several parameters that included pH, electrophoretic run buffer concentration, buffer type and the influence of chelating ligand in the electrophoretic run buffer were examined to determine the best separating conditions. Optimum separation of the six metal chelates was achieved in a 15 mM Na2B4O7–NaH2PO4, pH 8.3 buffer containing 0.1 mM TAR. Method validation included injection and method precision studies as well as detection limit and linear dynamic range determination. High-ppb to low-ppm (w/w ratio) detection limits were achieved with linear dynamic ranges between 0.1 and 75 ppm.