Polarographic Behavior of Metal Ions in the Presence of Polyethylene Glycol in Potassium Chloride1

Abstract

Abstract The polarographic behavior of Cu(II), Pb(II), Tl(I), Sn(II), In(III), Cd(II), and Zn(II) was investigated in the presence of polyethylene glycol (PEG) in 0.1 mol dm−3 potassium chloride. PEG was adsorbed on mercury drops within the potential range from ca.−0.2 through −1.50 V vs. SCE, and shifted the half-wave potentials of Sn(II), In(III), Cd(II), and Zn(II) toward the negative direction, leaving the wave heights unchanged. On the other hand, the polarograms of Cu(II), Pb(II), and Tl(I) were not affected by the presence of PEG. Linear relationships between the wave heights for Cu(II), Pb(II), In(III), Cd(II), Zn(II), and their concentrations were obtained in the presence of PEG. Among these ions, the polarographic waves of In(III) and Cd(II), whose reduction potentials are very close together, became well separated in the presence of PEG. It is, therefore, possible simultaneously determine In(III) and Cd(II) in this medium. Interference between In(II) and Pb(II) was observed in freshly prepared solutions. It is, however, feasible to precisely determine both ions by using PEG as a reduction potential-shift reagent for In(III) in order to eliminate the interference.