چكيده فارسي :
Heavy metals pollution as an important challenge has been in the center of attention in recent years due to the environmental matters and their deadly effects on human life and all living organisms. Cadmium is categorized as one of the deadliest heavy metals for human being which directly affects the liver, kidneys, lungs, the immune system even in trace concentrations[1]. Consequently, many separation techniques have been presented to extract cadmium. Different techniques introduced to detemine cadmium. Dispersive liquid-liquid microextraction (DLLME) as a novel powerful LLME method was develpoed in which the appropriate mixture of extraction and disperser solvent are injected into an aqueous sample by syringe. However, application water-miscible organic dispersive solvents in DLLME decrease the partition coefficient of analytes with respect to the extraction solvent [2]. Hence, some new methods were proposed to overcome this problem. In this technique an efficient emulsification process can be obtained by dispersion of a low-density extraction organic solvent directly into the aqueous phase (without the need of disperser solvent), enhanced by vortex agitation. The fine droplets formed could extract analytes toward equilibrium faster because of the shorter diffusion distance and larger specific surface area. After a certain period of extraction time, centrifugation is typically performed f or phase separation.Vortex-assisted solidified floating organic drop microextraction method has some advantages such as simplicity, rapidity, high enrichment factor, sensitivity, selectivity. In this study the facile and efficient method of vortex-assisted solidified floating organic drop microextraction was applied for separation/preconcentration and determination of lead in water samples using electrothermal atomic absorption spectrometry. 2-(3,4-Dihydroxyphenyl)-1,3-dithiane and 1-undecanol were used as chelating agent and extraction solvent respectively. The influential parameters were studied and optimized as pH 6, ligand amount 1 mg, volume of 1-undecanol 50 µL, extraction time 5 min, sample volume 50 mL. Under the optimum conditions, the linear range of 0.01-100 µg L-1 with the correlation coefficient (r2) 0.9980, the limit of detection (LOD) of 0.005 µg L-1 were obtained. The proposed method was successfully applied to determine the lead in water samples.
