Application of adsorptive stripping voltammetry to the determination of bismuth and copper in the presence of morin

Abstract

A new method is presented for the determination of bismuth and copper based on cathodic adsorptive stripping of complexes of Cu(II) and Bi(III) with 2′,3,4′,5,7-pentahydroxyflavone (morin) at a hanging mercury drop electrode (HMDE). The effect of various parameters such as pH, concentration of morin, accumulation potential and accumulation time on the selectivity and sensitivity were studied. The optimum conditions for determination of copper include nitric acid concentration 0.1M, morin concentration 0.6μM and accumulation potential of -300mV. Those conditions for the determination of bismuth include 0.15M acid concentration, 0.6μM morin and accumulation potential of -300mV. Under these optimum conditions and for an accumulation time of 60s, the measured peak current at -20 to 25mV is proportional to the concentration of copper and bismuth over the range of 0.2-130 and 5-50ngml -1, respectively. At high concentration of morin (35μM morin) and accumulation potential of -300mV (versus Ag/AgCl reference electrode) the peak current is proportional only to the concentration of copper and bismuth has no contribution to the current. At low concentration of morin (0.5μM morin) and accumulation potential of 100mV (versus Ag/AgCl reference electrode) the peak current is proportional only to the concentration of bismuth. The method was applied to the determination of copper and bismuth in some real and synthetic samples with satisfactory results. © 2003 Elsevier B.V. All rights reserved.