Synthesis of La3+imprinted polymer nanoparticles and their application for lanthanum ion determination via an indirect voltammetric method-coupled with competitive extraction of lanthanum in the imprinted polymer modified electrode

We describe an indirect method for the voltammetric determination of La(III) ion. It is based on competitive extraction of La(III) into an ion-imprinted polymer (IIP) on the surface of a carbon paste electrode (CPE). The nano-sized IIP was synthesized via suspension polymerization in silicone oil and deposited on the CPE. The IIP-modified CPE was then incubated with solutions containing Cu(II) and a solution containing both Cu(II) and La(III) ions. The oxidative stripping differential pulse voltammetric signal for Cu(II) was utilized to determine the competitively extracted quantity of Cu(II). The presence of La(III) reduces the quantity of electroactive lead ions in the IIP located on the CPE. No such effect was observed for the case of a non-imprinted CPE. The effect of various factors on response was optimized. The drop in the signal for Pb(II) as a result of addition of La(III) is proportional to the concentration of La(III). The voltammetric response is linearly related to the concentration of La(III) in the 0.5 to 70.0 μM range, and the detection limit is 0.1 μM an SNR of 3. The relative standard deviation is 3.08 % (for n=5). The electrode is selective for La(III) even in the presence of other lanthanide ions. The method was applied to the determination of La(III) in synthetic and in spiked real samples.