An extraordinarily sensitive voltammetric sensor with picomolar detection limit for Pb2+ determination based on carbon paste electrode impregnated with nano-sized imprinted polymer and multi-walled carbon nanotubes

A new nano-structured ion imprinted polymer (IIP) was synthesized by copolymerization of itaconic acid-Pb2+ complex and ethylene glycol dimethacrylate according to the precipitation polymerization. Itaconic acid played both roles of functional monomer and complexing agent to create selective coordination sites in a final imprinted polymer. A carbon paste electrode, concurrently impregnated with the IIP-nanoparticles and multi walled carbon nanotubes (MWCNTs), acted as a Pb2+ sensitive electrode. Square wave anodic stripping voltammetry (SWASV) method was applied as the determination technique, after open circuit sorption of Pb2+ on the electrode and its reduction to metallic form. The IIP/MWCNT-modified electrode showed a considerably higher response, compared to the electrode embedded with non-imprinted polymer (NIP). This indicated that efficient recognition sites were created in the IIP in the polymerization reaction. Various factors, influencing the response behavior of the electrode, were investigated and optimized. The introduced sensor exhibited a linear range of 1.0 x 10(-11)-8.0 x 10(-8) mol L-1 and detection limit of 3.8 pmol L-1 (S/N = 3). The electrode presented excellent sensitivity of 20683 A L mol(-1) and high selectivity toward Pb2+ over common potential interfering heavy metal ions. To further confirm the practical applicability of the sensor, it was successfully applied for the trace lead determination in different samples.