Spherical agarose-coated magnetic nanoparticles functionalized with a new salen for magnetic solid-phase extraction of uranyl ion

The authors describe a method for magnetic solid phase extraction of uranyl ions from water samples. It is based on the use of spherical agarose-coated magnetic nanoparticles along with magnetic field agitation. The salen type Schiff base N,N’-bis(4-hydroxysalicylidene)-1,2-phenylenediamine was synthesized from resorcinol in two steps and characterized by infrared and nucleic magnetic resonance spectroscopies. The particles were then activated by an epichlorohydrin method and functionalized with the Schiff base which acts as a selective ligand for the extraction of UO₂(II). Following preconcentration and elution with HCl, the ions were quantified by spectrophotometry using Arsenazo III as the indicator. The effects of pH value, ionic strength and amount of the adsorbent on the extraction of UO₂(II) were optimized by a multivariate central composite design method. Six replicate analyses under optimized conditions resulted in a recovery of 96.6 % with a relative standard deviation of 3.4 % for UO₂(II). The detection limit of the method (at a signal-to-noise ratio of 3σ) is 10 μg L￣¹. The method was successfully applied to the determination of UO₂(II) in spiked water samples.

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Graphical Abstract Spherical agarose-coated magnetic nanoparticles (SACMNPs) were prepared in the presence of Span 85 (a nonionic surfactant) and functionalized by a salen type Schiff base for magnetic solid-phase extraction of uranyl ion

     

Large-Scale Molecular Dynamics Simulations of Energetic Ni Nanocluster Impact onto the Surface

On the atomic scale, Molecular Dynamics (MD) Simulation of Nano Ni cluster impact on Ni (100) substrate surface have been carried out for energies of E _a = 1–5 eV/atom and total energy of E _T = 195 eV (the total energy of cluster is E _T = nE _a, n is the number of cluster atoms) to understand quantitatively the interaction mechanisms between the cluster atoms and the substrate atoms. The many-body Embedded Atom Method (EAM) was used in this simulation. We investigated the maximum substrate temperature T _max and the time t _max within which this temperature is reached as a function of cluster sizes and the total energy E _T. The temperature T _max is linearly proportional to total cluster energy. For the constant energy per atom and for the cluster size increase, the correlated collisions rapidly transfers energy to the substrate, and the time t _max approached a constant value. For constant total energy the temperature T _max and the time t _max versus different cluster sizes was studied. We showed that the cluster implantation and sputtering atoms from the surface are affected by the cluster size and total kinetic energy of the clusters. Finally time dependence of the number N _dis of disordered atoms in the substrate was observed.     

Microextraction of Rosmarinic Acid Using CMK-3 Nanoporous Carbon in a Packed Syringe

CMK-3 nanoporous carbon was prepared and used as an efficient sorbent for microextraction in packed syringe of rosmarinic acid in Rosmarinus officinalis L. (rosemary). In the proposed method, only 2 mg of the nanoporous material, inserted between a syringe’s barrel and needle, was sufficient for the extraction with minimum consumption of organic solvents. Sample preparation was performed on the packed bed using a laboratory-made programmable apparatus. The apparatus was designed and used for automation of the conditioning, sampling, washing and elution steps of the method, and increasing the reproducibility of the experiments. For optimization of the experimental parameters, a central composite design method was used. Under the optimized conditions (i.e., number of adsorption cycles 14 times, number of elution cycles ten times and volume of elution 100 μL), an extraction recovery of 90 (±4.5) % was obtained for rosmarinic acid. The same packing bed could be used for at least 80 extractions without significant changes in its properties. The efficiency of the nanoporous sorbent was found to be superior to that of activated carbon, by a factor of about 17. The proposed method was successfully applied to the extraction of three rosemary samples before analysis by HPLC.     

Study of the Essential Oil Composition of Cumin Seeds by an Amino Ethyl-Functionalized Nanoporous SPME Fiber

An ultrasound assisted SPME method with a new nanoporous SBA-15 fiber functionalized with 3-[bis(2-hydroxyethyl)amino]propyl-triethoxysilane was successfully applied to the study of the essential oil composition of cumin (Cuminum cyminum L.) seeds. The sample was irradiated by ultrasound radiation and its volatile components were collected by the fiber from the sample headspace and directly injected into a GC-MS injection port for analysis. A simplex method was used for optimization of four different parameters affecting the efficiency of the extraction. Under the optimized conditions (i.e. sample weight, 0.6 g; temperature, 70 °C; sonication time, 12 min and extraction time, 28 min), the number of components identified by the proposed method and their amounts were identical to those of a hydrodistillation technique. The extraction efficiency of the SBA-15 fiber was superior to a PDMS commercial fiber. The major components identified were p-menta-1,3-dien-7-al, cuminaldehyde, γ-terpinene and p-cymene, respectively. The proposed method was applied to a comparative study of the essential oil composition of cumin in three different climate conditions of the Lorestan province in Iran. The results indicated that the essential oils in the temperate and tropical locations were 94.0 and 85.6% of the cold region, respectively.     

Preparation of a Novel Agarose-Salen Adsorbent,and its Use for Efficient Column Preconcentration and Flame AAS Determination of Lead in Water

A cross-linked agarose (Novarose) support was chemically modified with a novel salen-type Schiffs base; 2,2-[1,2-ethandiyl bis(nitrilimethylidyne)] bis(orthocresol) and was used to develop an efficient, simple and low-cost method for matrix separation and preconcentration of lead in water. The binding capacity of the adsorbent, packed in a 6.5mm i.d. glass column, was tested for different metal ions, and a capacity of 4973 (±95) µg per mL of packed adsorbent for triplicate measurements was obtained for lead at pH 6.0.The effects of pH, ionic strength, buffer concentration, sample volume, eluent concentration and volume, and matrix ions on the column recovery of Pb²⁺ were carefully studied. Quantitative recoveries were obtained for the analyte in a pH range of 5.5 to 7.0. Enrichment volumes up to 300mL and ionic strengths up to 0.5molL^–1 had no significant effect on the recovery of Pb²⁺. The method also tolerated relatively high concentrations of matrix ions such as Ca²⁺, Mg²⁺, Fe³⁺, Cu²⁺, Zn²⁺, Mg²⁺ and Cd²⁺ with no considerable effect on the analytes signal. A few mL of 0.4molL^–1 hydrochloric acid was sufficient for quantitative elution of the analyte from a 0.5mL column before its flame AAS determination. Preconcentration factors up to 60 and a detection limit of 2.5µgL^–1 were obtained for the method. The precision, expressed as relative standard deviation, was 2.9% (at 100µgL^–1) calculated from six replicate measurements. The method was successfully applied to the determination of Pb²⁺ in some river and spiked river water samples with good precision.     

A highly sensitive method for the determination of mercury using vapor generation gold wire microextraction and electrothermal atomic absorption spectrometry

The study introduces a new simple and highly sensitive method for headspace solid phase microextraction (HS-SPME) coupled with electrothermal atomic absorption spectrometric determination of mercury. In the proposed method, a gold wire, mounted in the headspace of a sample solution in a sealed bottle, is used for collection of mercury vapor generated by addition of sodium tetrahydroborate. The gold wire is then simply inserted in the sample introduction hole of a graphite furnace of an electrothermal atomic absorption spectrometry instrument. By applying an atomization temperature of 600 °C, mercury is rapidly desorbed from the wire and determined with high sensitivity.     

A dual column system using agarose-based adsorbents for preconcentration and speciation of chromium in water

Three different agarose-based chelating adsorbents with, respectively, iminodiacetic acid (IDA), tris(2-aminoethyl)amine (TREN) and dipicolylamine (DPA) functional groups and an agarose-based anion exchanger (Q-Sepharose), were studied for the separation and preconcentration of Cr(III) and Cr(VI) species in water. Column recoveries of all the adsorbents were plotted against pH, and it was found that at pH 3.0 the IDA adsorbent selectively adsorbs Cr(III), with a 100 ± 1.0% recovery. The Q-Sepharose, on the other hand, accumulated only Cr(VI) at this pH, again with a recovery of 100 ± 1.0%. A dual column system was accordingly designed, using the two adsorbents in tandem, for the separation and preconcentration of the chromium species.The effects of pH, sample flow rate, column length, eluent type, eluent volume, acid concentration and interfering ions on the recoveries of Cr(III) and Cr(VI) were carefully studied. It was shown that by passing test solutions, at pH 3.0; through the dual column system, the two chromium species could be individually collected on the columns, respectively, and eluted, one after the other. A portion of 2 mol l⁻¹ hydrochloric acid was used for elution of each column before final measurement by flame AAS method. A preconcentration factor of 12, a detection limit of 7.7 ± 0.1 μg l⁻¹ and a precision expressed as relative standard deviation of 0.4% (at 0.3 mg l⁻¹) were achieved for six replicates.Application of the developed method to the determination of chromium species in spiked river and tap water and wastewater samples, from a dye production plant, resulted in excellent agreements with accepted concentrations.     

Chemical Compositions of the Essential Oils of Stems,Leaves, and Roots of <Emphasis Type="Italic">Prangos latiloba</Emphasis>

Hydrodistilled volatile oils from crushed dry stems, leaves, and roots of Prangos latiloba Korov. (Umbelliferae) growing wild in Sabzevar (Iran) were analyzed by GC and GC/MS. Eight compounds constituting 84.72% of stem oil, twelve compounds constituting 95.39% of leaf oil, and nine compounds constituting 88.73% of root oil have been identified. The main components of stem oil were γ-cadinene (30.39%), α-pinene (25.47%), and sabinene (12.55%). The main components of leaf oil were germacrene D (27.79%), α-pinene (17.81%), β-caryophyllene (12.75%), and β-pinene (11.23%). The main components of root oil were spathulenol (29.5%), 1,8-cineol (19.42%), p-cymene (17.03%), and α-bisabolol (15.33%). __________ Published in Kimiya Prirodnikh Soedinenii, No. 5, pp. 443–444, September–October, 2005.