S. Meloni

Adsorption of monovalent ions on zinc ferrocyanide

Abstract The adsorption from different solutions of caesium, rubidium, potassium, sodium, lithium, silver and mercury (I) on zinc ferrocyanide has been studied. The preparation of the adsorber and its characterization are presented and discussed. The sorption of the alkali metals appears to proceed by an ion-exchange mechanism in NH4NO3 solutions. In HNO3 solutions oxidation to zinc ferricyanide and the destruction of the adsorbed species influence the behaviour of the cations.

Provenance studies of obsidian artifacts: Trace elements analysis and data reduction

Iron and trace elements, such as rare-earth elements, scandium, rubidium, cesium, tantalum, thorium and uranium were determined by instrumental neutron activation analysis in geological samples of obsidian rocks from the Mediterranean Area and in obsidian artifacts found in some prehistorical human settlements in Italy. REE patterns and discriminant analysis allow a firm identification of the source material of artifacts, thus confirming and implementing fission track data of the same artifacts and rocks on the origin of the obsidian rock used to mould the artifacts.

Neutron Activation Analysis: a Powerful Tool for Assay of Rare-Earth Elements in Terrestrial Materials

Abstract Neutron activation analysis methods for determination of rare-earth elements in different matrices have been developed at the University of Pavia using the 250 Kw TRIGA Mark II reactor. A critical review of both instrumental and destructive methods is presented, as well as the indication of the best working conditions for irradiation, counting and radiochemical separations. The optimized procedures were utilized in the determination of rare-earth elements in standard reference materials of both mineral and biological origin. The adopted radiochemical procedure is based on the separation of the rare-earth element group by fluoride precipitation. Results, given as the average of six independent determinations and relative standard deviations, are reported and discussed. Precision of the methods can be deduced from the reproducibility of data, whereas accuracy is evaluated by comparison with existing values in the literature. Sensitivity limits under the described operational conditions are also reported, as are trends and correlations among data.

Characterisation of Armenian Obsidians: Implications for Raw Material Supply for Prehistoric Artifacts

Obsidians from occurrences located in Armenia have been analysed using neutron activation analysis, both instrumental and epithermal, in order to enhance the knowledge of characteristics of potential sources of raw material exploited during prehistory. An alternative characterization technique, the fission-track dating method, was also applied. Results contribute to increase the data-set for provenance studies of prehistoric obsidian artifacts in the Mediterranean and adjacent regions.

Sorption of divalent ions on zinc ferro- and ferricyanide

Abstract The adsorption of some divalent ions on zinc ferro- and ferricyanide in nitric acid solution was investigated. Distribution coefficients for divalent Ba, Cu, Zn, Hg, Ni, Co, Cd, Sn and Fe were measured by batch equilibration experiments. Adsorption mechanism was investigated relating the influence of zinc and caesium concentrations on the uptake of copper, cobalt and cadmium. At low metal concentration the adsorption appears to occur through an ion-exchange mechanism, whereas at high metal concentration the formation of mixed salts appears to affect the uptake of divalent ions. Equilibrium constant and solubility product relationships have been derived and discussed.

Platinum assay by neutron activation analysis and atomic absorption spectroscopy in cisplatin treated pregnant mice

Cisplatin (CDDP) is an antineoplastic drug used in the treatment of a wide variety of tumors. This paper describes an investigation carried out on pregnant mice after intragastric or intraperitoneally treatment with CDDP from day 11 to 13 of gestation. Platinum content in different tissues, namely liver, kidney, placenta and brain, was determined at 18 day of pregnancy. Two analytical techniques were used, i.e. neutron activation analysis and atomic absorption spectroscopy. Results of both techniques are presented and discussed in terms of precision, accuracy and sensitivity. Neutron activation analysis appears to provide results better correlated with the drug treatment.

Provenance studies of the white marble of the cathedral of Como by neutron activation analysis and data reduction

Marble samples from major Italian quarries and from the Como Cathedral were analyzed for their trace element content, which is indicative of their provenance. Ca, Sc, Cr, Mn, Fe, Co, Rb, Sb, Cs, Ba, La, Ce, Sm, Eu, Gd, Ho, Tm, Yb, Lu, Hf, Th and U elements were determined by neutron activation analysis. Results as well as their precision and accuracy are presented and discussed. Data treatment has allowed to characterize the marble quarries on the basis of their trace element content, to identify the provenance of the marble used in the Como Cathedral and to show differences in the element distribution of new and weathered marble samples from the same quarry.

Provenance studies of Roman amphorae by instrumental neutron activation analysis

Recently excavated roman amphorae were submitted to instrumental neutron activation analysis for the determination of Ca, Sc, Cr, Fe, Co, Sb, Ba, La, Ce, Eu, Yb, Lu, Hf and Th. Data reduction was carried out by identifying first the elements useful for discrimination purposes and then by submitting the data to cluster analysis. Amphorae are parted in two groups which are related to different provenance areas.

Determination of some noble metals and copper by destructive neutron activation analysis of different matrices

Neutron activation analysis of palladium, iridium, platinum, gold, silver and copper in different matrices was carried out by using inorganic adsorbers such as molybdenum dibromide, zinc ferrocyanide and cadmium metal for their radiochemical separation. The matrices chosen to show the versatility of the method were: high-purity copper and nickel metals, NBS standard reference material SRM 1571 (Orchard leaves), Pultusk meteorite and the U. S. Geological Survey standard rock W-1. The method elaborated is very simple as it involves only a few steps and it has been shown to be accurate and capable of yielding reliable results.

Trace elements distribution in Antarctic sediments by neutron activation analysis

In the present investigation iron and trace elements were determined by instrumental neutron activation analysis in a number of sea bottom sediment samples, collected in the Ross Sea and close to the Italian Station at Terra Nova Bay in Antarctica. Full listing of results is presented and discussed as well as the evaluation of precision and accuracy. In order to find correlations and similarities among the sediment samples, the analytical data were submitted to statistical treatment. In addition rare earth element patterns were obtained. Typical trends were observed with no evident Eu negative anomaly and a depletion of heavy rare earth elements.