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  • Author or Editor: K. Farah x
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Abstract  

Preparation of radioidinated L-α-methyl tyrosine by the oxidative radioiodination using chloramine-T (CAT) and iodogen (1,3,4,6-tetrachloro,-3α, 6α-diphenyl glycoluril) to generate electrophilic radioiodine has been carried out. The factors affecting the labeling yield such as pH of the medium, reaction time, substrate and oxidizing agent concentrations have been investigated to optimize the conditions for the preparation of radioiodinated L-α-methyl tyrosine in high radiochemical yields. Side product impurities were observed at long reaction times and high oxidizing agent concentrations. Maximum radiochemical yields of 89.7±1.5% and 87.8±1.6% were obtained in case of CAT and iodogen, respectively. Separation and purification by high pressure liquid chromatography (HPLC) resulted in radiochemically pure products. Using high specific activity123I, the SPECT brain imaging agent can be prepared.

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Abstract  

The extraction of Co2+ from aqueous 0.1M acetate buffer by thenoyltrifluoroacetone (HTTA) and 8-hydroxyquinoline (HQ) and by a mixture of HTTA+phen and HQ+phen in benzene has been studied at various temperatures allowing for elucidation of the thermodynamics of extraction in the cases investigated.

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Abstract  

The thermodynamics of the extraction of Eu3+ by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and bidentate amine bases such as 2,2-dipyridyl (Dipy) and 1,10-phenanthroline (Phen) in benzene from an aqueous phase fixed to 0.1M ionic strength (NaClO4), pH 3.9, has been investigated. Phenanthroline forms both the Eu(TTA)3·Phen and Eu(TTA)3·2Phen species, which are much stronger than the dipyridyl complexes. The diluent effect on the extraction is also studied.

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Abstract  

The extraction of Co3+ from 0.1M aqueous acetate medium buffered to pH 5.3 by thenoyltrifluoroacetone (HTTA) in benzene and by 8-quinolinol (HQ) also in benzene at various temperatures has been studied. The species formed were Co(OH)2 (TTA)·(HTTA)2 and Co(Q3)·2HQ, respectively. 1,10-phenanthroline (Phen) as a base was also mixed with HTTA to form the species Co(OH)2(TTA)·(HTTA). Phen and Co(OH)2 (TTA)(HTTA)·2Phen. No synergism was observed upon the addition of Phen to HQ.

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Abstract  

The squarate complexes of Eu3+, Tb3+ and Tm3+ in aqueous solutions of 0.05M, 0.075M and 0.1M ionic strength are studied using the solvent extraction method. Effects of changes in the ionic strength on the stability constants of the complexes formed are discussed.

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Abstract  

The adsorption behaviour of thorium, protactinium, uranium, neptonium and plutonium on zirconium phosphate from nitric acid and ammonium nitrate solutions was investigated. Partition data from the mentioned media together with that from chloride solutions were used to calculate formation constants for the concerned elements in the range of Cl and NO 3 activities <1M. Obtained β values were compared with those reported in the literature and indicated reasonable agreement.

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Summary  

A simple method for labeling ERC9 with radioactive iodine has been carried out via nucleophilic substitution radioiodination. The factors affecting the radiochemical yield of the labeling of ERC9, such as pH of the medium, substrate concentration and temperature were investigated. Chromatographic analysis technique was used to determine the radiochemical yield and purity. Kinetics and thermodynamic parameters indicated a second order reaction. Activation energy for the isotopic exchange reaction between ERC9 and 125I- was calculated to be 24.4 kJ/mol.

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Abstract  

Extraction of Eu3+ from 0.1M aqueous perchlorate medium by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and tributylphosphate (TBP), HTTA and triphenylphosphine oxide (TPPO), HTTA and trioctylphosphine oxide (TOPO) and HTTA and triphenylarsine oxide (TPAsO) has been studied at various temperatures allowing for the elucidation of the mechanism of extraction in each case and a comparison between the various bases.

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Abstract  

Sorption of Th, Pa, U, Np and Pu on silica gel from HNO3, HCl and HCl−ROH solutions was investigated. Equilibrium studies indicated sorption behaviour to vary greatly with the acid used. In mixtures of HCl with different alcohols, distribution coefficints were found to depend on alcohol percentage as well as on acidity. Results were discussed and conditions for possible separations were indicated.

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Abstract  

Sorption of124Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of124Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylenetoluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for124Sb(III) compared to124Sb(V),152Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents.

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