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We have developed a facile and highly sensitive sorbent for cadmium and lead ions. It is based on FeO nanoparticles functionalized with a derivative of picoline and was characterized by scanning electron microscopy, differential thermographic analysis, and elemental analysis. The material can be applied to the preconcentration of lead and cadmium ions. Factors such as the type, concentration and volume of eluent, the pH of the sample solution, the time for extraction, and the volume of the sample were studied. The effects of a variety of ions on preconcentration and recovery of these ions were also investigated. The ions were determined by FAAS, and the limits of detection are <0.8 and <0.061 μg L for lead and cadmium, respectively. Recoveries and precisions are >98.0 % and <1.3 %, respectively. The method was validated by analyzing several certified leaf reference materials. [ABSTRACT FROM AUTHOR]

A carbon paste electrode for determination of mercury (II) ions in real samples was prepared. The main objective of the present study was to evaluate the concentration of mercury ions in different soil, water, plant, and animal muscle samples by utilizing modified carbon paste electrode. Functionalized nanoporous MCM-48 and multi-walled carbon nanotubes material were used in order to increase the efficiency and selectivity of the electrode for mercury ions determination. The electrode composition material was optimized as graphite powder 57%, Paraffin 22%, modified MCM-48 16% and MWCNTs 5% (W/W). The linear range of the electrode was calculated 5.0×10-8 to 1.0×10-3 mol L-1, and a detection limit was obtained 1.5×10-8 mol L-1. The potential slope was achieved 29.7±1.0 mV, and lifetime for the electrode was investigated about 5 months. The proposed method was applied to a number of natural samples and the amount of mercury was determined. [ABSTRACT FROM AUTHOR]

The usage of tris(2-aminoethyl)amine-functionalized Fe3O4 nanoparticles as a novel magnetic sorbent for rapid extraction, preconcentration, and determination of trace amounts of silver and gold ions was investigated. The optimum conditions for sample pH, eluent parameters (type, concentration and volume) were obtained. The effect of various cationic interferences on the adsorption of silver and gold was evaluated. The analytical efficiency values of both silver and gold ions were higher than 98.0% in the optimum conditions. The limits of detection (LOD) were less than 0.8 and 0.5 ng ml-1 for silver and gold, respectively. The linear ranges for silver and gold were 1.5-1000 ng ml-1 and 1.0-1000 ng ml-1 respectively. The maximum capacity of the modified magnetic nanoparticles was more than 97.3 mg g-1 and 167 mg g-1 for silver, and gold ions, respectively. The presented method was used to determine silver and gold ions in real samples. Finally, the method accuracy was confirmed by standard reference materials. [ABSTRACT FROM AUTHOR]

A modified SBA-15 mesoporous silica was developed, as an adsorbent, for the removal of Cr(VI) ions from natural-water samples. The effects of experimental parameters, including pH of solution, sample and eluent flow rate, the eluent composition, the eluent volume, and the effect of coexisting ions on the separation and determination of Cr(VI), were investigated. It was shown that Cr(VI) was selectively adsorbed from aqueous solution at pH 3, but Cr(III) could be adsorbed from solution at alkaline pH range. The retained Cr(VI) was eluted with 0.5 mol L−1 KCl solution in 0.1 mol L−1 Na2CO3 subsequently. Under the optimum conditions, the modified mesoporous silica (py-SBA-15) with a high pore diameter exhibited an adsorption capacity of 136 mg g−1 and a lower limit of detection than 2.3 µg L−1 by using diphenylcarbazide as a chromophorous reagent for the determination of Cr(VI) ions. A preconcentration factor as high as 200 was calculated for Cr(VI). The loaded py-SBA-15 can be reactivated with recovery of more than 98.5% over at least eight cycles. The relative standard deviation (RSD) for Cr(VI) ion recovery was less than 1.8%. Validation of the outlined method was performed by analysing a certified reference material (BCR 544). The proposed method was applied to determine Cr(VI) value in natural and waste water samples successfully. [ABSTRACT FROM AUTHOR]

Nano-alumina modified by 9-aminoacridine was used as a sorbent for separation and determination of dichromate ions from water. Statistical method, based on surface response design, has been used for the optimization of dichromate ions elution from 9-aminoacridine nano-alumina. The adsorbed dichromate ions were found to be eluted quantitatively with 0.8 mol L−1 KCl in 1.6 mol L−1 NaOH which optimized by response surface design. Under optimum conditions, the accuracy, precision (relative standard deviation, RSD%) and R-square of the method were calculated as >98, <3, and >94%, respectively. Remarkable agreement between experimental and theoretical data was confirmed the predicted assumption. The method was applied to the simultaneous determination of dichromate in natural and industrial water samples. We also examined the retention of dichromate anions in the presence of Cl−, ${\rm NO}_{3}^{- } $, and ${\rm SO}_{4}^{2- } $ anions at pH 3. [ABSTRACT FROM AUTHOR]