Glutathione-Stabilized Silver Nanoparticles and Magnetic Nanoparticles Combination for Determination of Lead and Cadmium in Environmental Waters

A novel and highly sensitive method for the selective trace analysis for lead (Pb2+) and cadmium (Cd2+) ions was reported, based on glutathione-modified silver nanoparticles and Fe3O4 magnetic nanoparticles. The presence of Pb2+ and Cd2+ induces the aggregation of AgNPs through cooperative metal-ligand interaction, and the aggregations were loaded on Fe3O4 magnetic nanoparticles as sorbents. After adsorption, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase was eluted by HCl solution and determined by flame atomic absorption spectrometry. The effects of experimental conditions including pH of sample solution, the volume of GSH-AgNPs, the mass of sorbent, type and volume of eluent, the effect of foreign ions were evaluated in order to enhance sensitivity of the method. Under the optimal conditions, the enrichment factor of 60 was achieved with a sample volume of 10 mL. The detection limit of this method for Cd and Pb were 0.13 and 1.25 μg L–1, and the relative standard deviation were 1.5% and 1.8% at 10 μg L–1 concentration level of Pb and Cd, respectively. The method was successfully applied for these metals content evaluation in environmental water samples with satisfactory results.