A Polarographic Study of Chlorogenic Acid and Its Interaction with Some Heavy Metal Ions

Abstract

The behavior of chlorogenic acid (CGA) and its interaction with Hg(II), Pb(II), Cu(II), Cd(II) and Zn(II) has been studied using direct current (DC) and differential-pulse polarography (DPP). Adsorptive and kinetic/catalytic anodic waves of CGA have been detected at -0.02 and -0.18 V vs. SCE, respectively; Hg(I)-CGA surface disproportionation has been assumed. Reduction of Hg(II)-ions, added in the buffered solution of CGA (pH 7.5), occurs rather than complexation, while the complex forming ability of CGA towards Pb(II) and Cu(II) has been observed. Stoichiometry 1?:?1 for Pb(II)-CGA, and 1?:?1 and 1?:?2 for Cu(II)-CGA has been established applying Jobs method of continuous variation on DPP data. UV-vis spectrophotometric measurements additionally confirmed the existence and stoichiometry of Cu(II) complexes.