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1.
Flame atomic absorption determination of manganese(II) in natural water after cloud point extraction
The possibility to use 4-(2-pyridylazo)resorcinol (PAR) and 1-(2-pyridylazo)-2-naphthol (PAN) for manganese(II) concentrating by the micellar extraction at cloud point (CP) temperature and subsequent atomic absorption spectrometry (AAS) determination was investigated. Under the optimum conditions, preconcentration of 100 ml of water sample in the presence of 1% non-ionic surfactant (NS) OP-7, 1×10−4 M 1-(2-pyridylazo)-2-naphthol permitted the detection 5 μg l−1 manganese. The proposed method has been applied to the AAS determination of manganese in water samples after cloud point extraction. 相似文献
2.
Doroschuk VO Lelyushok SO Rakhilchuk OO Kulichenko SA 《Journal of colloid and interface science》2006,299(1):403-409
The influence of the concentration conditions, solutions acidity, and electrolyte additions on the lyophilic properties of the surfactant-rich phases of polyethoxylated alkylphenols OP-7 and OP-10 formed at cloud point temperature were studied. The lyophilic properties of surfactant-rich phases were determined by estimating of their effective hydration values and solvation free energy of methylene and carboxyl groups at cloud point extraction of aliphatic monocarboxylic acids. It was shown that the surfactant-rich phases formed from the dilute surfactant solutions have more hydrophobic properties than the phases formed from the high concentrated solutions. The possibility of changing the lyophilic properties of surfactant-rich phases by electrolyte additions was shown: complex formation between electrolyte cation and the polyoxyethylene chain of the surfactant increases the hydrophilic properties of the surfactant-rich phases. Calculations of the solvation free energy of methylene and carboxylic fragments of the aliphatic carboxylic acids at micellar extraction showed the uniqueness of the surfactant-rich phases which are able to energetically advantageously extract both hydrophilic and hydrophobic molecules of substrates. 相似文献
3.
The cloud point extraction of copper(II) with monocarboxylic acids into non-ionic surfactant phase 总被引:1,自引:0,他引:1
The possibility to use monocarboxylic acids and their mixtures with amines for copper concentrating by the way of micellar extraction at cloud point temperature, and later atomic absorption spectrometry (AAS) determination was investigated. Under the optimum conditions, preconcentration of 100 ml of water sample in the presence of 1% non-ionic surfactant OP-10, 0.005 M capric acid and 0.01 M octylamine permitted the detection of 0.01 μg ml−1 copper. The proposed method has been applied to the AAS determination of copper in water samples after cloud point extraction. 相似文献
4.
Doroschuk VO Kulichenko SA Lelyushok SO 《Journal of colloid and interface science》2005,291(1):251-255
The specificity of interphase transfer of organic reagents of different types between water and the nonionic-surfactant-rich phases at the cloud point temperature was investigated. In contrast to organic solvents, the ability of the micellar phases to extract highly charged ions of organic reagents was shown. Further evidence of the specificity of interphase transfer in micellar-extraction systems is independent and cooperative influence of substrate molecular structure and hydrophobicity on their distribution. The appearance of host-guest phenomenon in cloud point extraction systems that is inherent in organized systems with molecules of the receptors was established. The possibility of describing reagent distribution using regressions that consider substrate hydrophobicity and molecular structure in the cloud point extraction systems was shown. 相似文献
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6.
Volodymyr O. Doroschuk Anastasiya B. Grogul Yevhen S. Mandzyuk Oksana G. Makukha Nataliya O. Grytsyk 《Chemical Papers》2016,70(10):1316-1321
A new simple cloud point extraction/preconcentration method was developed for the HPLCMS/MS determination of disulfiram in synthetic urine. Some parameters with an effect on the extraction, such as the concentration of Triton X-114, pH influence, incubation time, equilibration temperature and centrifuging parameters, were studied and optimised. The method proposed for the HPLC-MS/MS determination of disulfiram in synthetic urine with preliminary cloud point extraction was validated. The calibration curve was linear in the range of 0.025–15.4 ng mL?1. The limits of detection (3σ) and quantification (10σ) were 0.008 ng mL?1 and 0.025 ng mL?1, respectively. The matrix effect (96 %), recovery of the extraction procedure (95 %) and overall “process efficiency” (91 %) were also estimated. The results show that the sensitivity, metrological characteristics, ecological safety, simplicity and convenience of the suggested procedure exceed its analogues based on extraction using organic solvents. 相似文献
7.
DAVID P. DOBSON JOHN P. BRODHOLT LIDUNKA VOČADLO WILSON A. CRICHTON 《Molecular physics》2013,111(10):773-777
Experiments have been performed at 5 GPa on liquid Fe-FeS in order to determine Fe and S self-diffusivity as a function of temperature. The viscosity of the sample was then obtained using the Stokes-Einstein relation. The results are in excellent agreement with previous experiments where the viscosity of a material of the same composition under similar conditions was measured directly. These results support high, near-metallic, values of diffusivity and low viscosity in liquid Fe-S up to a few hundred K above the eutectic temperature, in contrast with some previous studies. Moreover, these results fully confirm the validity of the Stokes-Einstein relation between viscosity and diffusion coefficients for Fe0.61S0.39. 相似文献
8.
SL Mironov E Skorova G Taschenberger N Hartelt VO Nikolaev MJ Lohse S Kügler 《BMC neuroscience》2009,10(1):29-11
Background
cAMP is an ubiquitous second messenger mediating various neuronal functions, often as a consequence of increased intracellular Ca2+ levels. While imaging of calcium is commonly used in neuroscience applications, probing for cAMP levels has not yet been performed in living vertebrate neuronal tissue before. 相似文献9.
Ilona Raspertova Roman Doroschuk Dmytro Khomenko Rostislav Lampeka 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(3):m61-m63
The structure of the title compound, [U(C14H9N3O2)O2(CH3OH)2]·CH3OH, is the first to be reported for an actinide complex including triazole ligands. The UVI atom exhibits a pentagonal–bipyramidal NO6 coordination environment, involving two axial oxide ligands [U=O = 1.766 (3) and 1.789 (3) Å], four equatorial O atoms [U—O = 2.269 (3)–2.448 (3) Å] from the ligand and the two coordinated methanol molecules, and one equatorial N atom [U—N = 2.513 (4) Å] from the ligand. In the crystal structure, the complex molecules are linked via intermolecular N—H...O and O—H...O hydrogen bonds to form a two‐dimensional structure. 相似文献
10.
Ilona V. Raspertova Roman O. Doroschuk Dmytro M. Khomenko Rostyslav D. Lampeka 《Journal of Coordination Chemistry》2017,70(16):2888-2899
Zinc and cadmium complexes, ML2(NO3)2 (L = N-methyl-C-(2-pyridyl)nitrone) were synthesized and characterized by means of X-ray diffraction crystallography and IR and NMR spectroscopy. The organic ligands in the complexes are coordinated via the oxygen atom of the nitrone group and the nitrogen atom of the pyridine moiety. The coordination environment of the central atoms is a distorted octahedron. The bond lengths and angles of the complexes were calculated using the DFT method with B3LYP functional. Theoretical studies revealed that the geometric parameters are in agreement with the experimental data. The fluorescent properties for the zinc and cadmium complexes were investigated at room temperature. 相似文献