Adsorptive stripping voltammetric behaviour of UO2(II) complexed with the Schiff base N,N′-ethylenebis(salicylidenimine) in aqueous 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid medium

The adsorptive stripping voltammetric behaviour of the uranyl ions complexed with the Schiff base SALEN in buffered aqueous solution of HEPES at the hanging mercury drop electrode (HMDE) versus Ag/AgCl (saturated KCI) was studied. The adsorptive stripping behaviour was evaluated with respect to Schiff base's concentration, supporting electrolyte and pH, potential and pre-concentration time, scan rate dependence and analytical application. It was found that, in the pH range from 6.3 to 8.0, UO2(II)-SALEN complex exhibited one large cathodic adsorptive reduction peak whose position depended on pH. Cyclic voltammetry showed that the reduction mechanism seemed to be quasi-reversible in the range of the scan potential rate employed. Due to the sensitivity of differential pulse adsorptive stripping current per unit of concentration, even with low accumulation time, a new method for the uranium determination in the presence of SALEN was studied. The response of the system was found to be linear in the range of uranyl concentrations from 5.0 to 25.0 mu g/l. A sensibility of 30 nA/10(-8) mMol with 120 s of pre-concentration time was achieved. The method was applied to uranium determination in a glass SRM-610-certified sample. (C) 2000 Elsevier Science B.V. All rights reserved.