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  • Author or Editor: F. Girardi x
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Abstract  

The development and applications of activation analysis in the period 1945–1980 are reviewed. In analysing the number of publications reported with time three periods can be distinguished: (a) A first period of slow development, up to 1960, in which the technique showed its very high sensitivity and demonstrated the importance of trace elements; (b) A second period of fast development (1960–1970) in which all aspects of the technique were developed; (c) A third period (after 1970) in which development occurred at a rate approximately equal to the average development rate of analytical chemistry, in terms of the number of publications reported. The present trends shows only minor developments in the methodology, while a good a potential for new and original applications is evident. The importance of a good scientific knowledge of the specific areas of applications is considered necessary to properly frame the analytical activities.

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Abstract  

A destructive method for the measurement of impurities in high purity zinc by neutron activation analysis is described. It essentially uses organic resins and inorganic exchangers for the separations. Sensitivities at the ppb level are obtained for a high number of elements.

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Abstract  

A new method is presented to remove sodium interferences from neutron-activated materials. The method is based on passage of the samples, dissolved in a concentrated acid solution on a column of hydrated antimony pentoxide (HAP). The retention is quantitative with a maximum capacity of 31 mg Na/g HAP. Only tantalum, in addition to sodium, was retained by HAP out of the 60 elements tested. The method should find applications in neutron activation analysis, particularly of biological materials. Applications are also foreseen in other analytical techniques, such as emission spectroscopy and flame spectrophotometry, where high sodium concentrations in the sample can be a source of interference.

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Résumé  

Cet article traite de l'utilisation d'échangeurs minéraux dans l'analyse destructive de matériaux de grande pureté, en particulier pour la détermination systématique d'un grand nombre d'éléments. On indique brièvement des améliorations récentes dans la méthode permettant d'évaleur mathématiquement les modes de séparation radiochimique à l'aide des échangeurs minéraux. On décrit les modes de séparation dans le cas du dosage des impuretés dans de l'aluminium et du zinc de haute pureté. Les résultats pour plusieurs échantillons de zinc obtenus par purifications successives sont donnés, ces résultats mettent en évidence l'évolution de la distribution des différentes impuretés. On présente aussi les résultats obtenus dans le cas d'un échantillon de zinc choisi comme étalon.

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Abstract  

The behaviour of 66 radio-ions towards 11 exchangers and 11 solutions under standardized experimental conditions has been evaluated and classified in order to have the possibility of a rapid assessment of radiochemical separation procedures. Two systems of utilizing the bulk of data obtained have been devised and employed. The first is based on the use of a deck of cards similar to those used for fast retrieval of bibliographic information, in which the behaviour of ions is coded by means of punched holes; the second is based on the treatment of the data by means of an electronic computer. The operational modes of the two systems and examples of their practical applications are presented.

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Abstract  

The presence of large quantities of32P in neutron activated biological specimens is often a limiting factor in the direct application of γ-ray spectroscopy. A technique for the selective removal of phosphates in neutron activated specimens is described. The technique is based on the adsorption of phosphates on chromatographic grade alumina. The adsorption selectivity was studied by determining the behaviour of 49 ions when submitted to the procedure for phosphate removal. A few applications are reported as examples.

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Abstract  

The retention of different radio-ions on columns of eleven ionic precipitates from different acid media was studied, in view of possible applications for radiochemical separations. The results of about 2,000 adsorption experiments, carried out in a standardized way, are presented schematically in periodic tables.

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Abstract  

A method of neutron activation analysis is described for the quantitative determination of phosporus in nucleic acids, nucleotides and glucose-6-phosphate in amounts of 0.1 to 200 μg, without any chemical separation. This technique may be usefully applied to the measurement of the phosporus content in organic materials and biochemical preparations. The procedure involves a short neutron activation in a nuclear reactor and measurement of the Cerenkov radiation emitted by the irradiated capsule after a suitable decay period. Possible interferences due to other induced radionuclides are discussed.

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Abstract  

In a framework of a more intensive study of the oceanographic phenomenology of the Northern Adriatic Sea, recently undertaken by the O. G. S. of Trieste, the present paper provides some insight into the determination of trace elements in sea water and bottom sediment matrices. Sampling procedure using continuous pumping and filtering and neutron activation analytical techniques are presented and the obtained results briefly discussed. Accounting for the physiography of the basin, for the oceanographic processes and for the different freshwater input, several samples were collected of filtered water in order to set up their properties. Results were obtained throughout the settlement only for long-lived radionuclides based on routine neutron activation: Cr, Ag, Co, Cs, Rb, Sb, Sc, Sr, Zn, U. For each of them, the concentration range was determined and discussed. Results indicate that the Cs, Rb, Sr and U concentration range is readily comparable with that assessed at open seas. On the contrary, for the other elements such as Cr, Ag, Co, Sc, Sb and Zn concentrations are noticeably higher than those found at open seas, mainly as far as samples collected near the sea bottom are concerned. The concentration increase is surely related to the burden of pollutants suffered by rivers. Moreover, the positive concentration gradient experienced toward the bottom, is fully in agreement with the estuarine character of the investigated area and in accordance with the strong decomposition of organic matter taking place in the bottom layer of the basin. Finally, the complexity of the sedimentary pattern in the Northern Adriatic renders it difficult to properly define the element concentration in bottom sediment. Only four samples were chosen as representative of the different sediments and analysed. Long-lived elements obtained are: Ce, Co, Cs, Cr, Rb, Sc, Tb, Yb. Their concentration was found to be related to the geochemical features of the activated matrix.

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Abstract  

Some typical applications of long-term/low-level exposure (LLE) is presented including in vivo LLE study on rats and in vitro experiments on some metal binding components as well as on cadimium binding protein.

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