Application of modified magnetic nanoparticles as a sorbent for preconcentration and determination of nickel ions in food and environmental water samples

A new solid-phase extraction sorbent was used for the separation/preconcentration of Ni(II) ions prior to their determination by flame atomic absorption spectrometry. It was prepared by immobilization of dithiooxamide on magnetic nanoparticles (MNPs) of magnetite (Fe3O4) coated with cationic surfactant sodium dodecyl sulfate. The properties of sorbent and MNPs were characterized by scanning electron microscope and transmission electron microscope. Some parameters affecting extraction, such as pH, adsorbent dosage, and eluent concentration and volume) were optimized. The calibration graph was linear in the range 30-5000 µg.L−1 with a limit of determination of 3.9 µg.L−1. The relative standard deviation for Ni ions was 1.3%. The method was applied to the determination of trace amounts of Ni(II) ions in water and food samples.