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Abstract  

A very sensitive and selective flow injection on-line determination method of thorium (IV) after preconcentration in a minicolumn having XAD-4 resin impregnated with N-benzoylphenylhydroxylamine is described. Thorium (IV) was selectively adsorbed from aqueous solution of pH 4.5 in a minicolumn at a flow rate of 13.6 mL min−1, eluted with 3.6 mol dm−3 HCl (5.6 mL min−1), mixed with arsenazo-III (0.05% in 3.6 mol dm−3 HCl stabilized with 1% Triton X-100, 5.6 mL min−1) at confluence point and taken to the flow through cell of spectrophotometer where its absorbance was measured at 660 nm. Peak height was used for data analyses. The preconcentration factors obtained were 32 and 162, detection limits of 0.76 and 0.150 μg L−1, sample throughputs of 40 and 11 h−1 for preconcentration times of 60 and 300 s, respectively. The tolerance levels for Zr(IV) and U(VI) metal ions is increased to 50-folds higher concentration to Th(IV). The proposed method was applied on different spiked tap water, sea water and biological sample and good recovery was obtained. The method was also applied on certified reference material IAEA-SL1 (Lake Sediment) for the determination of thorium and the results were in good agreement with the reported value.

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Abstract  

The extraction of the V(V)-BPHA complex into chloroform and benzene was investigated using48V tracer produced from the45V reaction using the Variable Energy Cyclotron, Calcutta. A neutron activation analysis procedure for the estimation of vanadium in gallium metal samples based on the extraction of V(V)-BPHA complex into benzene is given.

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Abstract  

The extraction of Y, La, Ce(III), Gd, Th, Fe(III), Co(II), Cu, Zn, Cd, Hg, In and Tl (I=0.1;T=20±2°C) with N-benzoyl-N-phenylhydroxylamine (N-BPHA) in chloroform has been studied in order to determine the composition, and the extraction and two-phase stability constants of the extracted chelates. The dissociation constant of N-BPHA in aqueous solution has also been determined.

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Abstract  

Extraction of Pr(III), Ho(III) and Er(III) has been studied in the pH range of 1–10 with N-benzoyl-N-phenylhydroxylamine (BPHA) in benzene. The separation was found to be quantitative in borate media from pH 7 to 10, at an ionic strength of 0.1M (H+, BO3 3–). The stoichiometric composition of the complexes under the optimal conditions of shaking time, pH and reagent concentration was formulated using slope analysis and found to be M(BPHA)3, where M=Pr(III), Ho(III) and Er(III). The effect of various masking agents shows that citrate, ascorbate, EDTA, oxalate, fluoride and phosphate form stable complexes with these rare earths as compared to BPHA. The decontamination factors for different cations with respect to these rare earths under the optimum conditions have been evaluated.

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Abstract  

The extractability of many metal ions in the form of benzoylphenylhydroxylaminates as a function of acidity and basicity and the re-extractability of the chelate complexes dissolved in chloroform are described. The extraction was carried out by 0.1M BPHA in chloroform and the re-extraction by acid, basic, cyanide, sulphide, fluoride, complexon, tartarate and citrate solutions. The usability of the BPHA as a reagent for the separation of metal ions is discussed. Some possible ways for separating metal ions by alternating extraction and re-extraction are reported.

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Summary  

In the present work an improvement of radiochemical neutron activation analysis for determination of nanogram levels of vanadium is described. The method is based on post-irradiation wet ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine (BPHA) forming a violet chelate complex in strongly acidic medium. For quality assurance purposes a procedure for determination of the overall chemical yield using spectrophotometry of the V-BPHA complex is described, and possible interferences are evaluated. The procedure was applied to the determination of vanadium in reference materials and selected food samples from Slovenia.

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Abstract  

The extraction of cerium(III) and lanthanum(III) by N-benzoyl-N-phenylhydroxylamine (N-BPHA) in chloroform has been studied in order to determine the composition and extraction constants of the extracted chelates. From the results obtained, the best conditions for the separation of cerium from lanthanum (separation factor about 200) have been predicted and experimentally verified.

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Abstract  

A radiochemical procedure for the consecutive separation of vanadium and molybdenum, copper, manganese, rubidium and potassium is proposed for the analysis of biological materials. Vanadium and molybdenum are extracted together with 0.1% BPHA solution in toluene, copper followed by manganese are extracted as diethyldithio-carbamate complexes with chloroform and rubidium and potassium are precipitated as tetraphenylborates.

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Abstract  

Destructive and non-destructive methods have been used for the determination of microtraces of antimony in high-purity silicon powder. The destructive method was based on substoichiometric radioactivation analysis with solvent extraction using BPHA and cupferron as organic reagents. The antimony contents in high-purity silicon can be determined by the proposed method.

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Abstract  

The reduction reaction mechanism of carrier-free125Sb in HCl solution was studied kinetically. Sb(III) and Sb(v) were separated by solvent extraction using n-benzoyl-n-phenylhydroxylamine(BPHA) in chloroform at different constant time in interval and the reaction rate was determined by measuring the radioactivities of125Sb in both organic and aqueous phases. Plot of log[125Sb(V)/ [125Sb(III)+125Sb(V)] against the elasped time do not give straight lines. The curves can be solved to be ABC type reactions by a non-linear squares. On the basis of dependence of the reactions, overall reactions can be expressed as follows;

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