Optimized solid phase extraction based on diethyldithiocarbamate-coated Fe3O4 magnetic nanoparticles followed by ICP-OES for determination of Cd(II) and Ni(II) in rice and water samples

In the present study, application of Fe3O4 magnetic nanoparticles (MNPs) coated with diethyldithiocarbamate as a solid-phase sorbent for extraction of trace amounts of cadmium (Cd2+) and nickel (Ni2+) ions by the aid of ultrasound was investigated. The analytes were determined by inductively coupled plasma-optical emission spectroscopy. Fe3O4 MNPs were prepared by solvothermal method and characterized with dynamic light scattering, scanning electron microscope and X-ray diffraction. Response surface methodology was used for optimization of the extraction process and modeling the data. The optimal conditions obtained were as follows: chelating agent, 1.2 g L−1; pH, 6.13; sonication time, 13 min and Fe3O4 MNPs, 10.3 mg. The calibration curves were linear over the concentration range of 1–1,000 μg L−1 for Cd2+ and 2.5–1,000 for Ni2+ with the determination coefficients (R2) of 0.9997 and 0.9995, respectively. The limits of detection were 0.27 μg L−1 for Cd2+ and 0.76 μg L−1 for Ni2+. The relative standard deviations (n = 7, C = 200 μg L−1) for determination of Cd2+ and Ni2+ were 2.0 and 2.7 %, respectively. The relative recoveries of the analytes from tap, river and lagoon waters and rice samples at the spiking level of 10 μg L−1 were obtained in the range of 95–105 %.