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Abstract  

A new sub-superequivalence method of radiometric analysis is proposed, which is derived by combining the sub-superequivalence method of isotope dilution analysis with substoichiometric radiometric analysis. This method using redox reaction is applied for the determination of trace amount of antimony and was proved to be an excellent technique. The fundamental problems of this method are discussed analytically.

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Redox substoichiometry in isotope dilution analysis

V. The use of potassium bromate as the oxidizing agent in the analysis of metallic zinc for antimony

Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Kambara, J. Suzuki, H. Yoshioka, and Y. Watanabe

Abstract  

Radiometric titration of antimony(III) with potassium bromate in hydrochloric acid media using the standard series method provided much valuable informations on the titration errors which depended on the concentrations of the acid and antimony(III). The hydrochloric acid concentrations between 2.5 and 3.0M were found to be optimum for the oxidation of antimony(III) amounts of 4 μg or less. Under these optimum reaction conditions the redox substoichiometric isotope dilution analysis was applied to the determination of antimony in metallic zinc and the satisfactory results were obtained, without the separation of matrix element. Also, the merits of various oxidizing agents hitherto studied for the quantitative oxidation of antimony(III) were compared and discussed.

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Redox substoichiometry in isotope dilution analysis

II. Determination of antimony content in metallic zinc

Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Kambara, J. Suzuki, H. Yoshioka, and N. Nakajima

Abstract  

Isotope dilution analysis using the redox substoichiometric principle has been applied to the determination of antimony content in metallic zinc. As the substoichiometric reaction, the oxidation of trivalent to pentavalent antimony with potassium permanganate was used, followed by separation of these species by the BPHA extraction of trivalent antimony. Determination of antimony contents less than 0.5 μg was found to be possible with good accuracy, without separation of zinc ions. The antimony content in metallic zinc was determined to be 19.7±0.8 ppm, in good agreement with the results obtained by the other analytical methods.

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Abstract  

A radiometric method based on the redox substoichiometry has been developed for the determination of tellurium. The oxidation of tellurium(IV) to tellurium(VI) with potassium dichromate was employed as the substoichiometric reaction, followed by TBP (tributyl phosphate) extraction of the unreacted tellurium(IV) as the substoichiometric isolation. The oxidation of tellurium(IV) with dichromate under the substoichiometric conditions was incomplete. The chemical yield of tellurium(VI) produced by the oxidation of tellurium(IV) with dichromate was 83%. It was found that a tellurium content of 50 to 160 g could be determined with an accuracy of ±1.3% by means of the comparison method.

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Redox substoichiometry in isotope dilution analysis

IV. Determination of antimony content in metallic tin

Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Kambara, J. Suzuki, H. Yoshioka, and Y. Ugai

Abstract  

The oxidation reaction of antimony(III) with potassium dichromate has been investigated radiometrically. The quantitative oxidation of antimony(III) was found to be not disturbed even in large amounts of tin(IV). On the basis of these results the redox substoichiometric isotope dilution analysis using potassium dichromate as the oxidizing agent was proposed for the determination of antimony in metallic tin. The antimony content of 1.22±0.05 μg in metallic tin (10 mg) was determined without separation of the matrix element.

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Abstract  

Variations of125Sb valency states in HCl solutions were investigated by the use of the N-benzoyl-N-phenyl-hydroxylamine (BPHA) extraction method.125Sb(V) is completely reduced to Sb(III) by one hour refluxing in conc. HCl.125Sb(III) is gradually oxidized to Sb(V) in solutions of low HCl concentrations by the effects of their own radiations. Natural light promotes such oxidation reactions. By utilizing such oxidation-reduction effects125Sb(V) can be easily prepared from125Sb(III) and also125Sb(III) can be prepared by the reduction of Cl aq . Their valency states were stable on keeping them in brown-colored bottles at 6M HCl concentrations.

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