Effect of polyethylenimine on the selectivity of determining silver(I) by stripping voltammetry in the presence of copper(II)

It has been proposed that a water-soluble complexing polymer, polyethylenim ine (PEI), be used to lower intermetallic interactions at the surface of so lid electrodes in the determination of Ag(I) by stripping voltammetry in th e presence of Cu(II). The introduction of PEI in the binary Ag(I)-Cu(II) sy stem weakened the effect of Cu(II) on the anodic peak of Ag(I) and enhanced the selectivity in determining Ag(I) in the presence of excess amounts of Cu(II). With the use of PEI, Ag(I) can be determined at a Cu(II)-to-Ag(I) c oncentration ratio of 1000 : 1, compared to that of 20 : 1 in the absence o f the polymer.