A Preconcentration Procedure for Determination of Ultra-Trace Mercury (II) in Environmental Samples Employing Continuous-Flow Cold Vapor Atomic Absorption Spectrometry

New functionalized magnetic nanoparticles as solid-phase sorbent were prepared and investigated for extraction of ultra-trace amounts of mercury from environmental samples. The Fe3O4 magnetic nanoparticles functionalized with dithizone were characterized by Fourier transform infrared spectrometer. X-ray diffraction and scanning electron microscopy confirmed the size of nanoparticles. Effects of several factors on the extraction procedure were investigated. The optimized conditions were established to be 80 mg of polymer, 8.5 for solution pH, 5 min for adsorption time, 5 min for desorption time, 2 mL for HCl (0.1 mol L-1)/ thiourea 0.05 % as the eluent, 500 mL for breakthrough volume, and without addition of salt. Under the optimal conditions, the limit of detection, maximum capacity, and preconcentration factor were 0.05 ng mL(-1), 0.557 mmol g(-1), and 250, respectively. Limit of quantification was in the range of 0.2-2 ng mL(-1) for various matrices. Accuracy and precision of the method were about +/- 2.0 and below 11.1 %, respectively. Finally, the present method has been successfully applied to mercury determination in table salt, green tea, vegetables, toothpaste, and water samples. The mercury content found in the real samples was from 0.6 to 15.74 ng mL(-1) without addition of mercury.