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  • Author or Editor: U. Brinkman x
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Abstract  

For the system liquid anion-exchanger—Cr(III)−NCS, an investigation has been made of the dependence of the percentage extraction of Cr(III) on parameters such as standing time of the Cr(III)−NCS solution, temperature, pH and type of exchanger. Quantitative extraction of e.g. 4·10−4 M Cr(III) by 0.1M Aliquat in CCl4 is easily achieved at room temperature, using 4.75M KNCS−0.05N HCl as aqueous phase. At high Cr(III) concentrations, the complex anion present in the organic phase is Cr(NCS) 6 3− ; when working with dilute metal ion solutions, the species extracted is Cr(NCS)4 (H2O) 2 . Separations of mixtures containing 10−2−10−4 M Co(II), Ni(II) and Cr(III) have successfully been accomplished.

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Abstract  

The efficiency of a separation of metal ions by combining a displacement or exchange reaction and a liquid-liquid extraction procedure is calculated as a function of parameters such as pH, the ratio of the concentrations of reagent and analyte and the ratio of the concentrations of reagent and interfering ions. The resulting equations can be used to optimize separation conditions in activation analysis and to calculate favourable conditions for multielement isotope dilution analysis, the application of which is discussed.

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Abstract  

An investigation has been made on the system liquid anion-exchanger-Cd(II)-NCS. The influence of the acidity and thiocyanate concentration of the aqueous phase on the extraction has been studied. Using various methods of analysis, it has been shown that the complex anion present in the organic extracts is Cd(NCS) 4 2− . Details are given concerning the removal of traces of Zn(II) from Cd(II)-containing solutions, and the quantitative separation of Cd(II) from Cr(III).

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Abstract  

A theoretical concept is derived for multielement isotope dilution analysis in a liquid-liquid extraction system. The practical performance is based on radiometric titration. To that purpose a prototype of a titration/extraction vessel with flow injection has been constructed. For calculations of the initial concentrations of the elements of interest from the experimental data, a computer program has been developed.

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Abstract  

A program has been developed for the calculation of partition equilibria in the case when metal ions are extracted from an aqueous phase into an immiscible organic solvent containing a chelating reagent. Given the extraction constants and the initial concentrations, titration curves are constructed which show the extraction percentage of each ion in the presence of the others. The program is applied to hypothetical situations both in activation analysis and isotope dilution analysis.

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Abstract  

The use of on-line -detection in HPLC of radioactive-labelled samples is hampered by the time lag between the (relatively) fast separation and the slow counting. In the present approach, this difficulty is overcome by introducing a storage loop in which the eluate is temporarily stored, interspaced by a non-mixing liquid which may be the scintillator itself. The apparatus developed enables the determination of radiochromatograms which contain a total activity of 10 Bq.

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Abstract  

The characteization of a -detector for on-line radio-HPLC in terms of sensitivity, effective volume, peak efficiency and limits of determination, detection and decision is dissussed.

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