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51.
A new method for the preconcentration and determination of indium was developed using fiber optic linear array detection spectroscopy
(FO-LADS) combined with liquid-liquid microextraction (DLLME). DLLME was performed with rapid injection of a mixture containing ethanol (disperser solvent) and chloroform (extraction
solvent) into water sample containing indium after complex formation using 1-(2-pyridylazo)-2-naphthol (PAN) reagent that resulted in the formation of a cloudy solution. After centrifuging, fine droplets of chloroform, which were
dispersed among the solution and extracted In-PAN complex, sedimented at the bottom of the conical test tube. The concentration
of enriched analyte in the sedimented phase was determined by FO-LADS. The optimized method exhibited a good linearity (R
2 = 0.993) over the studied range (2–300 μg/L), illustrating a satisfactory precision level with standard deviation (RSD, n = 5) lower than 4%. The detection limit was 0.3 μg/L, and the enhancement factor of 160 was obtained. The proposed method
was compared with other methods and successfully applied to the analysis of several real and standard samples with satisfactory
results. 相似文献
52.
A new simple and sensitive method has been developed for the determination of trace levels of inorganic species in environmental water samples. It is based on the use of supramolecular?Cbased dispersive liquid?Cliquid microextraction (SM?CDLLME) prior to microsample introduction into FAAS. The ions are micro?Cextracted with coacervates composed of reverse micelles made from decanoic acid and dispersed in tetrahydrofuran?Cwater mixtures. Cobalt ion was used as a model ion, and 1?C (2?Cpyridylazo)?C2?Cnaphthol as the complexing agent. SM?CDLLME results from a combination of DLLME with coacervation?Cbased microextraction. It combines the advantages of DLLME with those of preconcentration based on coacervation and reverse micelles. Factors affecting the extraction efficiency of Co and its subsequent determination by FAAS were optimized. Under the optimized conditions and using 5.00?mL sample only, the enhancement factor is 58, the limit of detection is 4.2???g L?C1, and the relative standard deviations for 100???g L?C1 and 30???g L?C1 of Co are 2.1% and 3.8%, respectively (n?=?6). The accuracy of the method was confirmed by parallel analyses using the ASTM reference method.
Schematic representation SM?CDLLME enrichment method (Supramolecular assemblies were hired as extraction media in dispersive liquid?Cliquid microextraction. This method is based on microextraction of analytes with coacervates made up of decanoic acid reverse micelles dispersed in tetrahydrofuran (THF)?Cwater. Hazardous organic solvents as the microextraction solvent were avoided) 相似文献
53.
Masoud Salavati-Niasari Ghazaleh Banaiean-Monfared Hamid Emadi Morteza Enhessari 《Comptes Rendus Chimie》2013,16(10):929-936
In current study, nanoparticles of NiS were synthesized by applying microwave radiation. The effect of concentration of sulfur source, reaction time, and power of microwave irradiation on the treatment process was investigated. The morphology, structure, and composition of the as-synthesized nanostructures have been confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical properties of as-prepared sample were investigated by photoluminescence spectroscopy; the emission peak is at 555.04 nm and shows the blue shift. 相似文献
54.
Farzaneh Shemirani Shiva Dehghan Abkenar Aazam Alsadat Mirroshandel Masood Salavati Niasari Reyhaneh Rahnama Kozania 《Analytical sciences》2003,19(10):1453-1456
A rapid, sensitive and accurate atomic absorption method for Cr(III) and Cr(VI) ions was developed based on the cloud-point extraction (CPE) technique. Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the surfactant micelles. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of concentrated H2SO4 and ethanol to the sample solution. The condensed surfactant phase containing the metal chelates is introduced into an atomic absorption spectrometer. The relative standard deviations were 2.1% for both species and the limits of detection were around 0.17 microg l(-1). 相似文献
55.
Farzaneh Shemirani Reyhaneh Rahnama Kozani Mohammad Reza Jamali Yaghoub Assadi Mohammad-Reza Milani Hosseini 《International journal of environmental analytical chemistry》2013,93(14):1105-1112
The possibility of using Thio-Michler's Ketone (TMK), 4,4′-bis(dimethylamino) thiobenzophenone, for palladium(II) concentrated by micellar extraction at the cloud-point temperature, and later spectrophotometric determination, was investigated. Under the optimum conditions, preconcentration of 50?mL of water samples in the presence of 0.1% (w/v) octylphenoxy polyethoxy ethanol (Triton X-114), 2?×?10?6?mol?L?1?TMK and 1?×?10–3?mol?L?1 buffer solution (pH?=?3.0) gave the limit of detection of 0.47?ng?mL?1, and the calibration graph was linear in the range of 2–50?ng?mL–1. The recovery under optimum working conditions was higher than 97%. The proposed method has been applied to the spectrophotometric determination of palladium(II) in natural water samples after cloud-point extraction with satisfactory results. 相似文献
56.
Farzaneh. Shemirani Aazam Alsadat. Mirroshandel Masood. Salavati Niasari Reyhaneh Rahnama Kozani 《Journal of Analytical Chemistry》2004,59(3):228-233
A method for the preconcentration of Cd(II), Cu(II), Zn(II), and Ni(II) is proposed using a minicolumn filled with silica gel modified by Schiff's base. The retained analytes on the ligand-coated silica gel were recovered with a small volume of HNO3 (nitric acid). The metal ions in the eluent were determined by flame atomic absorption spectrometer (FAAS). Different factors, including the pH of the sample solution, the sample volume, the amount of silica gel, eluent volume and matrix effects for preconcentration were examined. The recoveries for the analytes under optimum working conditions were higher than 95%. The relative standard deviations of the determination were 1.50, 2.10, 2.40, 3.43% for Cu(II), Cd(II), Zn(II) and Ni(II). The limits of detection (3s, n = 10) for Cd(II), Cu(II), Zn(II), and Ni(II) were found to be 3, 5, 5 and 4.7 ngL–1. The proposed method was applied to the analysis of some natural water samples and standard reference aluminum alloy material (NBS SRM 85b). 相似文献
57.
A streamline upwind formulation is presented for the treatment of the advection terms in the general transport equation. The formulation is monotone and conservative and is based on the discontinuous nature of the advection mechanism. The results of there benchmark test cases for the full range of flow Peclet numbers are presented. The new formulation is shown to accurately model the advection phenomenon with significantly smaller numerical diffusion than the existing methods. The results are also free of all spatial oscillations. Considerable savings in computer storage and execution time have been achieved by employing the three-noded triangular element for which exact integrations exist. The formulation is straightforward and can be readily incorporated into any finite element code using the conventional Galerkin approach. 相似文献
58.
Ghazaleh Imani Shakibaei Ramin Ghahremanzadeh Ayoob Bazgir 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1305-1311
Abstract A highly efficient and green method for the synthesis of new 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids is described using magnetically recoverable and reusable CuFe2O4 nanoparticles. A wide variety of aryl isatylidene malononitrils underwent Micheal addition with thioacids to afford novel 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids in good to excellent yields. The reaction protocol is operationally simple and mild. Moreover, water as solvent makes the reaction procedure eco-friendly and economically viable. All products were characterized by NMR and IR spectroscopies. 相似文献
59.
Microchimica Acta - Non-modified molybdenum disulfide (MoS2) is known to adsorb heavy metal ions. However, in case of very small particle sizes and high dispersibility, ordinary centrifugation and... 相似文献
60.
A new synthesized modified mesoporous silica (MCM-41) using 5-nitro-2-furaldehyde (fural) was applied as an effective sorbent for the solid phase extraction of uranium(VI) and thorium(IV) ions from aqueous solution for the measurement by inductively coupled plasma optical emission spectrometry (ICP OES). The influences of some analytical parameters on the quantitative recoveries of the analyte ions were investigated in batch method. Under optimal conditions, the analyte ions were sorbed by the sorbent at pH 5.5 and then eluted with 1.0 mL of 1.0 mol L−1 HNO3. The preconcentration factor was 100 for a 100 mL sample volume. The limits of detection (LOD) obtained for uranium(VI) and thorium(IV) were 0.3 μg L−1. The maximum sorption capacity of the modified MCM-41 was found to be 47 and 49 mg g−1 for uranium(VI) and thorium(IV), respectively. The sorbent exhibited good stability, reusability, high adsorption capacity and fast rate of equilibrium for sorption/desorption of uranium and thorium ions. The applicability of the synthesized sorbent was examined using CRM and real water samples. 相似文献