Thiol-rich polyhedral oligomeric silsesquioxane-modified magnetic nanoparticles for the highly efficient separation and preconcentration of Cd(ii) and Pb(ii) in food and water prior to ICP-OES determination

A new protocol for the separation and preconcentration of Cd(ii) and Pb(ii) in some food and water samples was developed using thiol-rich polyhedral oligomeric silsesquioxane-modified magnetic nanoparticles (Fe3O4@SiO2/POSS-SH). The as-prepared magnetic adsorbent was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetoscopy. Cd(ii) and Pb(ii) were measured by ICP-OES after elution with 1 mL 1.0 mol L-1 HNO3. The influences of the analytical parameters including pH, eluent, sample volume, contact time and co-existing ions have been investigated in detail. The limits of detection were found to be 0.08 and 0.12 g L-1 for Cd and Pb, respectively, with an enrichment factor of 100. The proposed method was validated by two certified reference materials and applied successfully for the determination of Cd(ii) and Pb(ii) in rice, mushroom, pork, apple juice, bottled water and tap water with satisfied recoveries.