Synthesis of nano-sized Eu3+-imprinted polymer and its application for indirect voltammetric determination of europium

Abstract

Europium(III)-imprinted polymer nanoparticles were synthesized using suspension polymerization in silicon oil. Vinyl pyridine and methacrylic acid were used either as the complexing ligand or functional monomer. Divinyl benzene was applied as cross-linker agent. Carbon paste electrodes, impregnated with the ion imprinted polymer (IIP), were incubated in the solutions containing Cu2+ and different kinds of lanthanide ions. The oxidative stripping differential pulse voltammetry method was then utilized to measure the signal of adsorbed Cu2+, after removal of the electrodes from the first solutions and immersion of them in the electrochemical cell. The response of the IIP-modified electrode to Cu2+ decreased in the solution containing both Cu2+ and Eu3+; but, it was not influenced in the solutions of Cu2+ and other lanthanides. This suggested that Eu3+ could compete against Cu2+ to capture the selective sites of the IIP; whereas, other lanthanide ions were not capable of replacement with Cu2+ in the IIP sites. However, In the case of non-imprinted polymer (NIP)-modified electrode, no considerable signal difference was found between the pure Cu2+ solution and the solution containing both Cu2+ and Eu3+. This indicated that the selective sites of the IIP were responsible for the observed phenomenon. The decrease in the response of IIP-based electrode to Cu2+ was found to be reasonably proportional to Eu3+ concentration. This finding was utilized for the indirect voltammetric determination of Eu3+. The effect of different factors on the method was then investigated and the optimum conditions were chosen. The electrode showed high selectivity for Eu3+, even in the presence of other lanthanide ions. The developed method exhibited concentration linear range of 5×10−7–3×10−5molL−1 and detection limit of 1.5×10−7molL−1 (signal/noise, S/N). Relative standard error percent of 5 separate determinations was found to be 2.91%. The developed method was successfully applied for the determination of Eu3+ in the synthetic and spiked real samples.