Magnetic Solid ‒ Phase Extraction of Trace Amounts of Nickel in Food Samples Using Polydopamine Coated Fe3O4 Nanoparticles

A simple and a green methodology has been developed for the preconcentration of Ni2+ based on the adsorption of its dimethylglyoximate complex on polydopamine coated Fe3O4 nanoparticles. The adsorbed complex was easily desorbed using 1.0 mL of CHCl3 and the concentration of nickel was determined by UV-Vis spectrophotometry. The effects of pH, sorbent mass, extraction time on the sorption of nickel dimethylglyoximate complex were investigated using Box–Behnken design. In optimal experimental conditions, a wide linear range of 5.0-600.0 μg/L with detection limit of  1.49 μg/L was obtained. The proposed method was applied for extraction and preconcentration of Ni2+ in various food samples and the results were compared with the official AOAC method.