Selective Solid-Phase Extraction and Trace Monitoring of Lead Ions in Food and Water Samples Using New Lead-Imprinted Polymer Nanoparticles

A solid-phase extraction method using Pb2+ ion-imprinted polymer (Pb2+-IIP) nanoparticles combined with flame atomic absorption spectrophotometry (FAAS) was developed for the preconcentration and trace monitoring of lead ions in environmental samples. The Pb2+-IIP nanoparticles were obtained by precipitation polymerization of 4-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2'-azobisisobutyronitrile (the initiator), 4-(2-pyridylazo) resorcinol (the lead-binding ligand), and lead ions (the template ion) in acetonitrile solution. The Pb2+-IIP nanoparticles were characterized by Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TGA/DTA), and by scanning electron microscopy (SEM). Different affecting parameters on the adsorption and desorption of this solid-phase extraction process were evaluated and optimized. Under the optimized conditions, the detection limit for the proposed method was found to be 0.9 mu g L-1, while the relative standard deviation (RSD) for five replicate measurements was calculated to be < 4 %. For proving that the proposed method is reliable, a range of food and water samples with different and complex matrices was used.