F. Girardi

Radiochemical separations by retention on ionic precipitate adsorption tests on 11 materials

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.

The selective removal of32P from activated specimens in neutron activation analysis

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.

The capability of neutron activation for trace element analysis in sea water and sediment samples of the Northern Adriatic Sea

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.

Application of gamma ray spectrometry and computer techniques to the determination of the minimum detectable content of trace elements in neutron activated materials

Abstract A computer method has been developed in order to derive from the gamma ray spectrum of a neutron activated material the detection limits for a great number of trace elements. A “sensitivity spectrum” is calculated from the experimental data. The detection limit for 57 elements is then deduced using library data of specific activities. With this procedure it has been made possible to determine, in a sample of nuclear graphite, detection limits smaller than 1 ppm for about 40 elements. The performances of a 3″ × 3″ NaI(Tl) scintillator and of a lithium drifted germanium semiconductor detector for this particular application are compared. The computer program is written in FORTRAN-4 for the IBM 7090 computer.

Application of neutron activation analysis to metallobiochemistry

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.

Some recent developments in radioactivation analysis: A review of improvements in the analytical technique

Abstract The different techniques of activation analysis are considered and recent basic or technical improvements are reviewed. Developments in related fields such as radiochemistry or γ-ray spectrometry are reported only when especially referring to activation analysis. Specific applications of activation analysis to the different fields have not been reviewed, unless they lead to improvements of the technique. Bibliographic references on applications are given.

APPLICATION OF LITHIUM-DRIFTED GERMANIUM SOLID-STATE DETECTORS TO THE DETERMINATION OF HAFNIUM IN ZIRCONIUM OXIDE BY ACTIVATION ANALYSIS

absorbent paper, and the box is heat-sealed for irradiation. After irradiation, each vial can be opened by supporting it in a one-hole rubber stopper and slicing off one end with a knife. Marking polyethylene is done by scoring with hot metal and rubbing the wax from a china marking pencil into the depressions. Neat alphabetic and number marks can be made with a set of metal punches which are warmed in a flame.

Cerenkov counting rates of radionuclides for activation analysis purposes

Cerenkov counting efficiencies for a large number of radionuclides formed by (n, γ) reactions and used in the field of activation analysis have been obtained by two different experimental procedures. A comparison between the Cerenkov counting technique and scintillation low-resolution gamma-ray spectrometry is also presented. Results are summarized in tables and briefly discussed.

NON-DESTRUCTIVE ANALYSIS OF PHOSPHORUS BY NEUTRON ACTIVATION ANALYSIS IN BIOCHEMICAL PRODUCTS

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.

Determination of calcium, strontium and barium in single crystals of alkali halides by neutron activation

The determination by neutron activation of trace quantities of calcium, strontium and barium in single crystals of alkali halides has been studied. The matrix is eliminated before the irradiation by an ion-exchange procedure. Gamma spectroscopy after radiochemical separation is used to determine strontium and barium. Calcium is determined by measuring the β-activity of 49Sc formed by the decay of 49Ca. Long-lived radioactive tracers are used to determine the chemical yields.