Synthesis, characterization and analytical application of Zn(II)-imprinted polymer as an efficient solid-phase extraction technique for trace determination of zinc ions in food samples

Zinc imprinted polymer (Zn(II)-IIP) as a solid-phase extraction technique was applied for preconcentration and determination of zinc in environmental and food samples by FAAS. Zn(II)-IIP was synthesized by copolymerization of 2-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, 2,2-azobisisobutyronitrile as the initiator, Zn(NO3)2 as the template ion, diphenylcarbazone as the ligand, and methanol/dichloromethane (50:50) as the solvent. The synthesized polymer particles were characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), and X-ray diffraction (XRD). The optimization process was carried out using the central composite design (CCD). With this design, the optimum conditions for the adsorption step were 6.6, 30 mg, and 23 min, for pH, mass of polymer and adsorption time respectively, and for desorption step the optimal conditions were 14 mL, 12% (v/v), and 23 min, for volume of eluent, concentration of eluent, and desorption time, respectively. Under the optimized conditions, the detection limit of the proposed method was found to be 0.15 μg L−1, while the relative standard deviation (RSD) for 10 replicate measurements was calculated to be 2.8%. Therefore the introduced selective solid phase extraction method can be used as a reliable technique for selective and sensitive trace detection of zinc in different food matrixes, and the reliability of the proposed solid phase extraction technique was established by the analysis of standard reference materials.