Kinetic studies of the electrode and dissociation reactions of uranyl-DTPA complexes by polarographic method

Abstract

The uranium-DTPA chelate gives a two-step irreversible reduction wave when the concentration of surface-active substance, Triton X-100, is greater than 0·003%, due to the adsorption of surface-active substance on the mercury electrode. The limiting current of the first wave is controlled partially by the rate of electrode reaction. The electrode reaction of the second wave is a rate-determining step corresponding to the dissociation of the uranyl-DTPA chelate. The rate constants of the electrode and dissociation reactions were determined. The limiting current and the rate constants are a function of the concentration of Triton X-100. The dissociation rate constants are pH dependence and correlated by the equation k 1 − = −3·47 log [H +] −13·2.