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  • Author or Editor: N. Suzuki x
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Abstract  

Substoichiometric methods are eminently suitable for the determination of many elements. As a new application of substoichiometry, a substoichiometric speciation of the element in different chemical states is proposed. Substoichiometric speciation of As(III) and As(V) is demonstrated as an example. This is based on a highly selective substoichiometric extraction of As(III) with thionalide and As(V) with tetraphenylarsonium chloride in the presence of an excess amount of pyrogallol. Coexistence of other diverse arsenic species including methylarsenic compounds does not give any interference to the selective determination of As(III) and As(V). For substoichiometric radioactivation, a novel application of the synergistic extraction system in a combination of a substoichiometric amount of thenoyltrifluoroacetone with an excess amount of phenanthroline is demonstrated for Yb as an example. Substoichiometric speciation based on the selective speration and an application of synergistic extraction to substoichiometric separation have additional possibilities in substoichiometry.

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Résumé  

Depuis qu'une nouvelle méthode d'analyse par activation basée sur la substoechiométrie a été proposée, un certain nombre de techniques ont été développées pour rechercher les éléments à l'état de trace. La nouvelle technique se décompose en (1) la méthode directe, (2) la méthode du traceur en quantité variable, (3) la méthode par comparaison. Ces méthodes ont les avantages suivants: la correction du rendement chimique n'est pas nécessaire, les réactions nucléaires secondaires et l'autoabsorption ne constituent pas des causes d'erreur dans le dosage. On décrit le principe de ces métho des et la détermination d'éléments à de très faibles concentrations dans les matériaux de haute pureté par les méthodes (2) et (3).

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Abstract  

A new type of synthetic multi-element reference material (SyRM) with pseudo-biological matrix was prepared by a co-polymerization reaction of an aqueous solution of acrylamide and acrylic acid containing known amounts of the elements. SyRM has the excellent homogeneity and the quantitative retention of major and trace elements. Elemental composition can simulate the biological samples to be analyzed. SyRM can be used for the same purpose of conventional certified reference materials with high accuracy and precision. SyRM was applied as a comparative standard for non-destructive photon and α-particle activation analysis. Selective preconcentration methods combined with NAA were proposed and the SyRM containing about fifty elements with known amounts was prepared. In order to evaluate the reliability of present methods, 3d transition elements and rare earth elements were determined in the SyRM. It was clearly observed that these methods have good accuracy and precision in trace analysis of biological materials by comparing the analytical results with the original contents in the SyRM. The SyRM supported multielement analysis of marine macro-algae can be used as comparative standards for the quality assurance of analytical techniques.

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Abstract  

A review of the substoichiometry in trace analysis is presented. The principle of the method, practical applications and recent developments are described.

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Abstract  

The synergic extraction of La(III), Nd(III), Sm(III), Tb(III) and Lu(III) with 0.1M acetylacetone (Hacac) and 1,10-phenanthroline (phen) in benzene was studied. The adduct formation constant, s, for RE(acac)3 (phen) in benzene was determined. The s decreases with inceasing atomic number of RE(III). The s in different organic solvents can be predicted in connection with the activity coefficients of the solutes, and the validity of this prediction is confirmed by good agreement with the experimental values of s in carbon tetrachloride and heptane.

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Abstract  

Partition coefficients of Cu(acac)2 were determined in eleven organic solvents-0.10M perchlorate systems. Their magnitude was compared with that of the enol form of Hacac and evaluated by a modified equation based on the regular solution theory. The partition coefficient of the copper (II) chelate has been demonstrated to strongly depend on some specific solute-solvent interactions such as direct coordination to the central metal and hydrogen bonding to the ligand molecules. In the case of chloroform, particularly the specific interaction has been elucidated by an association reaction, for which the equilibrium constant has been determined.

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Abstract  

Recent works on the trace analysis of various materials by activation analysis are summarized. INAA and IPAA are applied for the multielement determination of various standard reference materials and electronic materials. As an example, the analytical results of pepperbush and fluoride glass are shown. In activation analysis using chemical separation, the destructive neutron activation analysis coupled with isotope addition technique is presented and applied to the determination of trace impurities in indium phosphide. Selective substoichiometry and substoichiometric separagtions of some elements are also introduced.

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Abstract  

The combined use of photon activation and γ-γ coincidence spectrometry is described for the useful and selective nondestructive determination of nickel in geological materials. This method is characterized by the utilization of the nuclide emitting β+ particles in its decay and γ-γ coincidence counting with two gates: one for the annihilation photopeak region and the other for the higher Compton plateau region. The practical detection limits by this method for nickel, arsenic, rubidium, sodium and scandium in silicate matrices could be set at 2.0, 1.2, 9.0, 110 and 1.4 μg, respectively.

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Abstract  

Tropolone-5-sulfonic acid was used to separate and collect trace elements as their complexes onto an anion-exchange resin in photon-activation of biological materials. Retention behaviour of the anionic complexes of Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb on Dowex 1-X8 resin was examined with respect to pH, amount of resin, concentration of the ligand, and coexisting salt anions, using radioisotope tracers. Under optimum conditions, Cr, Mn, Co, Ni, Zn and Pb were collected from the irradiated samples of NBS-SRM Orchard Leaves, NBS-SRM Spinach, green tea and black tea on the marcket. The analytical results agreed with certified values and the reproducibility was good.

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