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 Cu(2+) and different kinds of lanthanide ions. The oxidative stripping differential pulse voltammetry method was then utilized to measure the signal of adsorbed Cu(2+), 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 Cu(2+) decreased in the solution containing both Cu(2+) and Eu(3+); but, it was not influenced in the solutions of Cu(2+) and other lanthanides. This suggested that Eu(3+) could compete against Cu(2+) to capture the selective sites of the IIP; whereas, other lanthanide ions were not capable of replacement with Cu(2+) in the IIP sites. However, In the case of non-imprinted polymer (NIP)-modified electrode, no considerable signal difference was found between the pure Cu(2+) solution and the solution containing both Cu(2+) and Eu(3+). 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 Cu(2+) was found to be reasonably proportional to Eu(3+) concentration. This finding was utilized for the indirect voltammetric determination of Eu(3+). The effect of different factors on the method was then investigated and the optimum conditions were chosen. The electrode showed high selectivity for Eu(3+), even in the presence of other lanthanide ions. The developed method exhibited concentration linear range of 5 × 10(-7)-3 × 10(-5)mol L(-1) and detection limit of 1.5 × 10(-7)mol L(-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 Eu(3+) in the synthetic and spiked real samples.