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1.
M. Hahn C. Voigt H. H. Rüttinger H. Matschiner 《Fresenius' Journal of Analytical Chemistry》1992,344(7-8):311-315
Summary The coupling is described of coulometric separation methods with an ion exchange separation step. Various methods of enrichment and separation are described using the analysis of nitrogen compounds, such as ammonia, urea and nitrite, as examples. A microcomputer controls the separation step and regulates the coulometric determination. Quantitative separations are achieved in all cases, so that the advantage of coulometric titration, as a precise absolute determination method, is retained. 相似文献
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Gold in iron ore samples is separated from iron (major matrix cation), antimony and vanadium using anion exchange resin in (0.2 M) HBr, potassium peroxodisulfate and acetone:water:nitric acid media. The exchangeable anion Cl− of the ion exchanger Dowex 1X 4 is replaced by Br− using (6 M) HBr solution. Certified reference material DGP-M1, spiked ferric magnetic oxide, gold radioactive tracer 198Au and gold standard solutions are used to study the adsorption efficiency and the yield recovery of tetrabromoaurate AuBr4− from the resin. Ten eluents have been tried to elute gold from the column, and it has been found that a 10 ml potassium peroxodisulfate and 240 ml acetone:water:nitric acid [125:5:5] solution fulfills the objective. The set up of the separation procedure allows quantitative adsorption of gold by the resin, while the major matrix cation (Fe) and others (Cd, Ag, Cu, V, Sb, Ti) have been passed through the column with the feeding solution (0.2 M) HBr. The resin selectivity coefficient (K) of separating Au from Fe has been found to be KFeAu≈6.4×1011. The eluted Au is treated with K2S2O8 and H2O2 for spectrophotometric determination as rhodamine-B complex at 555.6 nm. The linearity, detection limit, precision, and accuracy of the determination method have been found to be up to 2.0 μg g−1, 0.018 μg g−1, 0.009 μg g−1 and 3%, respectively. 相似文献
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C. Sepúlveda Munita L. T. Atalla 《Journal of Radioanalytical and Nuclear Chemistry》1985,91(1):135-148
The aim of the present work is to obtain the separation of233Th from the radioisotopes formed in the irradiation of Mn, U, Ba, Cs, Co and the lanthanide elements with thermal neutrons, because they may interfere in the neutron activation analysis of Th, when the activity of233Th is used. The experiments were performed with the resin Bio-Rad AG 50W X-4 and X-8 (100–200 mesh) in the thorium form. The separation of233Th from the interfering radioisotopes is based on the retention of233Th by the resin (isotope exchange) and the elution of the interfering radioisotopes with a dilute solution of Th in 0.5M HCl. Batch experiments were made in order to determine the equilibrium time for the isotopic ion exchange of thorium and also the distribution coefficients of the interfering elements between the solution and the resin. Column experiments were carried out with the purpose of establishing the conditions that allow the maximum isotope exchange of233Th and the minimum retention of the interfering radioisotopes in the resin. With this purpose, a statistical interpretation of a four variable experimental design is presented.From a thesis submitted by C. Sepúlveda Munita to the Instituto de Pesquisas Energéticas e Nucleares (CNEN/SP) University of São Paulo, in partial fulfillment of a Doctor of Science's Degree. Work supported by the Brazilian Atomic Energy Commission. 相似文献
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Summary Aliphatic anionic surfactants, like alkylsulfonates, alkyl sulfates, -sulfo alkanoic acids and their esters, were separated with respect to their alkyl chain length by high performance liquid chromatography (HPLC) using reversed phase (RP) columns. For sensitive and specific detection of these classes of compounds the HPLC separation was combined with a post-column ion-pair extraction system. The limit of detection is in the range of 3–30 ng. Previously reported detection systems of this kind were modified by changing the inner set-up of the phase separator and the extraction capillary and integrating a purge function, which led to a higher system stability and made automatization possible. In order to optimize the experimental set-up, the influence of the reagent concentration as well as different sizes and materials of the extraction capillary were evaluated. The calibration curve of surfactant concentrations versus fluorescence emission is discussed for sodium decylsulfonate. Since both the electrolyte concentration and the percentage of organic solvents in the mobile phase may adversely affect the detection system, different eluent compositions were tested.This article is part of the planned dissertation of Markus Schoester at the Mathematical Natural Science Faculty of the University of Düsseldorf 相似文献
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The magnesium isotope effects were investigated by chemical ion exchange with a hydrous manganese(IV) oxide. The capacity of manganese(IV) oxide was 0.5 meq g(-1). The distribution coefficient of magnesium ions on the MnO(2) was determined by a batch method. The heavier isotopes of magnesium were enriched in the solution phase, while the lighter isotopes were enriched in the hydrous MnO(2) phase. The separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assays. The separation factors of (24)Mg(2+)-(25)Mg(2+), (24)Mg(2+)-(26)Mg(2+), and (25)Mg(2+)-(26)Mg(2+) isotope pair fractionations were 1.011, 1.021, and 1.011, respectively. 相似文献
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P. Cable-Dunlap J. J. DeGange L. S. Nichols D. C. Duckworth S. H. Park G. J. van Berkel 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(1):177-181
Summary The International Monitoring System is part of the global verification system of the Comprehensive Nuclear-Test-Ban Treaty and comprises an atmospheric radioactivity monitoring network of 80 particulate stations, 40 of which are to be equipped with noble-gas-detection capability. The network is supported by 16 radionuclide laboratories. The equipment has to be tailored to different environments and its reliability is proving to be an operational challenge. 相似文献
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Won‐Keun Son Sang Hern Kim Tae Il Kim 《Journal of Polymer Science.Polymer Physics》2000,38(23):3181-3188
We calculated the characteristics of a phosphoric cation exchanger and studied an accurately computable method for ion exchange capacity for a type of potentiometric titration curve. The ion exchanger was prepared by phosphorylation of a styrene‐divinylbenzene copolymer. The ion exchange capacity was 5.7 meq/g. The experimental pK values versus χ in a phosphoric cation exchanger can explain a linear equation. The ΔpK values were obtained from the slope of a linear equation. The ΔpK values were the differences of pK values between the apparent equilibrium constant at complete and zeroth neutralization of the ion exchanger. The experimental pK values at χ = 0.5 (χ:degree of neutralization of ion exchanger) showed good agreement with the theoretical data. When it was titrated with NaOH and Ba(OH)2 solutions, a good agreement between experimental and theoretical pK values for various χ was found in all potentiometric titration curves. The potentiometric titration curve near the inflection point in the case of divalent ions was changed more sharply than that for monovalent ions. The plot of ∂pH/∂g versus g (number of moles of alkali to 1 g of ion exchanger) was fitted to the Lorenzian distribution, from which ion exchange capacity was accurately evaluated. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3181–3188, 2000 相似文献
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Mixtures containing large amounts of gold and small amounts of mercury (50:1) can be quantitatively separated by passing a 2N hydrochloric acid solution of the chlorides through Dowex 50 resin. Mercury behaves as a cation and is quantitatively retained. Gold behaves as an union and is not retained by the resin. The gold is obtained spcctrobcopically free from all metals. The capacity of the resin is approximately 10 nig of mercury per gram of rebin. The rcyin is freed from mercury by washing with 2N liydroclonc acid and may be used over again. 相似文献
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E. I. Shabana M. I. El-Dessouky M. M. Abed El-Aziz 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(2):293-296
Two antimonic acid samples were prepared and designated as hydrolyzed (H-SbA) and refluxed (R-SbA) antimonic acids. Their structure and ion exchange behavior towards Na+ as a simple ion is investigated. R-SbA samples showed higher degree of crystallinity and slightly higher ion exchange capacity than the other sample although it had slightly lower water content. Thermal treatment of both samples showed an increase in their ion exchange capacity on heating up to 200 °C. On further heating up to 400 °C the capacity is appreciably decreased. Equilibria measurements of both samples in dilute solutions showed almost an ideal ion exchange behavior. The obtained data are discussed in detail. 相似文献
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N. R. Das 《Journal of Radioanalytical and Nuclear Chemistry》1987,109(2):413-418
A simple ion exchange procedure for clean separation of the biomedically important radionuclide,90Y, in the equilibrium mixture,90Sr–90Y, has been demonstrated. Separation of90Y in the carrier-free state has been achieved by preferential elution of the radiotracer through a cation exchange resin column of Dowex-50W-X8 with freshly prepared Na-ascorbate solution of <1% concentration at pH7. The radionuclidic purity of the separated90Y has been verified by taking recourse to the studies of beta decay curves. The procedure developed has the added advantage that the complexing reagent, ascorbic acid, itself has got its own biomedical importance as vitamin C and the technique can also conveniently be used as a generator for the isotope90Y. 相似文献
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M. Dermelj Z. Šlejkovec P. Stegnar V. Čoh K. Čujes M. Novič 《Journal of Radioanalytical and Nuclear Chemistry》1992,164(1):59-69
On the basis of tracer experiments, a simple and rapid radiochemical separation method for simultaneous determination of I–, Br– and Cl– in one aliquot of a water sample (only 2–4 ml) has been developed. The method is based on short irradiation of the water sample and separation of the halogens using sequential ion exchange columns filled with Dowex 1×8, 100–200 mesh anionic resin prepared in I–/I2, Br–/Br2 and Cl– form. After washing the columns with an appropriate volume of 2% NaCl solution, the resins were transferred to vials and activities of the isolated radionuclides128I,82Br and38Cl measured together with standards in a well type or on a coaxial Ge detector connected to a Canberra 90 multichannel analyzer. Besides high chemical yields, from the -spectra of the isolated radionuclides, it is evident that high decontamination fac-The paper was presented at the MTAA-8, Vienna, September 1991. 相似文献
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Shikano K. Kudo K. Kobayashi K. 《Journal of Radioanalytical and Nuclear Chemistry》1982,74(1-2):73-84
The separation of fluorine was studied by several inorganic ion exchangers. A high yield of adsorption for fluorine was obtained
using hydrated tin dioxide in 1N nitric acid. Fluorosilicate can be separated under the same conditions. It was also found
that fluorine and fluorosilicate could be separated substoichiometrically. The substoichiometric separation was applied to
the determination of oxygen in silicon crystals by radioactivation analysis. The concentration of oxygen was 28 ppm and agreed
with that from a non-destructive method. 相似文献
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Michael Dion Greg Eiden Orville Farmer Zach Finch Martin Liezers 《Journal of mass spectrometry : JMS》2016,51(8):591-595
A technique that uses the intrinsic mass‐based separation capability of a quadrupole mass spectrometer has been used to resolve spectral radiometric interference of two isotopes of the same element. In this work the starting sample was a mixture of 137Cs and 134Cs and was (activity) dominated by 137Cs. This methodology separated and ‘implanted’ 134Cs that was later quantified for spectral features and activity with traditional radiometric techniques. This work demonstrated a 134Cs/137Cs activity ratio enhancement of >4 orders of magnitude and complete removal of 137Cs spectral features from the implanted target mass (i.e. 134). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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P. U. Singare R. S. Lokhande S. R. D. Tiwari 《Russian Journal of General Chemistry》2010,80(10):2054-2058
The thermodynamic study was carried out to predict the selectivity behaviour of ion exchange resin Indion-850 towaed various
inorganic anions like chloride, iodide, sulfate, and oxalate. The equilibrium constant K
std values for the ion exchange reactions were calculated at different temperatures from which the enthalpy values where obtained.
The K
std values were observed to increase with the rise in temperature, indicating endothermic ion exchange reactions. The thermodynamic
data obtained here reveal that iodide ions were more strongly retained on the resin surface compared to chloride ions. Also
the low enthalpy and high equilibrium constant values for oxalate ions indicate the greater selectivity of ion exchange resin
for oxalate ions as compared to sulfate ions. 相似文献
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《International journal of mass spectrometry》2000,194(1):41-48
The performance of an electrostatic ion guide for use in chemical ionization mass spectrometry is evaluated. The study focuses on the use of the ion guide to extract charged particles in a rapidly expanding beam consisting of ions and neutral molecules. A theoretical analysis of this system is presented, using three-dimensional calculations of the trajectories of ions. Laboratory measurements verifying the theoretical calculations are also reported. The results illustrate the two principal advantages for this system: efficient ion transmission and ion–neutral molecule separation. A comparison between the ion guide and the commonly used electrostatic ion lenses shows that the ion guide is significantly more efficient in capturing and transporting charged particles from a diverging ion source. 相似文献