[en] The authors describe the preparation of a nanocomposite (mag-MoS₂-Fe₃O₄) that was prepared from molybdenum disulfide (MoS₂) and magnetic Fe₃O₄ nanoparticles by a hydrothermal method in an inert atmosphere. The composite is shown to be a viable magnetic adsorbent for dispersive solid phase microextraction of lead(II) and copper(II) ions from water and plant samples. The nanocomposite was characterized by FT-IR, Raman spectroscopy, XRD, SEM, and BET methods. The factors affecting the extraction recovery of the analytes, including the pH value, type of dispersive solvent, sample volume, type and volume of eluent solution, and interfering ions, were optimized. Flame atomic absorption spectrometry was then used for quantitation. Figures of merit of this method include a preconcentration factor of 50 for lead(II) and 35 for Cu(II), LODs of 3.3 μg·L⁻¹ for lead(II) and of 1.8 μg·L⁻¹ for Cu(II), and RSDs of 4.9 and 1.5%, respectively. The method was used to preconcentrate the analytes from plant and water samples prior to their determination by FAAS. It was then validated by analyzing certified reference materials (water and plant), and this resulted in good accuracy. .

[en] Nanosized single crystal orthorhombic Bi₂WO₆ was synthesized by a hydrothermal method and used as a sorbent for vortex assisted solid phase extraction of lead(II). The crystal and molecular structure of the sorbent was examined using XRD, Raman, SEM and SEM-EDX analysis. Various parameters affecting extraction efficiency were optimized by using multivariate design. The effect of diverse ions on the extraction also was studied. Lead was quantified by flame atomic absorption spectrometry (FAAS). The recoveries of lead(II) from spiked samples (at a typical spiking level of 200–400 ng·mL⁻¹) are >95%. Other figures of merit includes (a) a detection limit of 6 ng·mL⁻¹, (b) a preconcentration factor of 50, (c) a relative standard deviation of 1.6%, and (d) and adsorption capacity of 6.6 mg·g⁻¹. The procedure was successfully applied to accurate determination of lead in (spiked) pomegranate and water samples. .