Thiodiethanethiol Modified Silica Coated Magnetic Nanoparticles for Preconcentration and Determination of Ultratrace Amounts of Mercury, Lead, and Cadmium in Environmental and Food Samples

A new magnetic adsorbent, 2,2 '-thiodiethanethiol grafted with tetraethyl orthosilicate modified Fe3O4 nanoparticles, was developed for the separation and preconcentration of Hg, Pb, and Cd in environmental and food samples. The concentrations of Pb and Cd were determined by inductively coupled plasma-optical emission spectrometry; Hg was determined by cold vapor atomic absorption spectrometry. A comprehensive study on the factors affecting the extraction and desorption efficiencies was performed. Under the optimized conditions, the method was linear in the 0.01-750ngmL(-1) range (before preconcentration) with detection limits of 4, 8, and 2ngL(-1) for Hg, Pb, and Cd, respectively. Relative standard deviations of 2.3, 2.9, and 2.4% (concentration 50ngmL(-1), n=7) and high preconcentration factors of 291, 285, and 288 were also obtained for Hg, Pb, and Cd. The accuracy of the proposed method was validated by analyzing a water certified reference material with satisfactory recoveries. The method was successfully applied to the determination of the analytes in tap and mineral waters and canned tuna fish samples.