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Abstract  

A selective method is described for the determination of210Pb in sediments, based on the separation of the daughter210Bi by extraction chromatography with Microthene 710-tri-n-octylphosphine oxide (TOPO) and on a final source counting with a low background -counter. The average chemical yield is 92.0%. The detection limit for 2 g samples is 19 Bq kg–1. An IAEA reference sediment sample was analyzed to check the reliability of the method.

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Abstract  

A sensitive and reliable metbod for the sequential separation and determination of plutonium,241Am and90Sr in soil samples was developed. Plutonium was separated by a Microthene-TNOA column. Then90Y (for90Sr determination) was separated from americium by a HDEHP column after elimination of large amounts of interfering stable or radioactive nuclides (iron,210Bi and210Po etc.) by an oxalate precipitation and a Microthene-TNOA column. Finally americium was purified by another HDEHP column and a PMBP-TOPO extraction. A special attention was paid to the decontamination of Pu and Am from210Po and of90Y from210Bi; the relevant decontamination factors resulted greater than 105, 106 and 104 respectively. The detection limits were 1.2 mBq/kg for Pu and 1.7 mBq/kg for241Am and 0.32 Bq/kg for90Sr. The procedure was checked by analyzing three certified samples supplied by IAEA. Some Italian soil samples were also analyzed giving average yields of 84.9±7.2% for Pu, 57.8±3.2%for Am and 96.7±1.6% for Y; the239+240Pu,238Pu,241Am and90Sr contents (Bq/kg) ranged from 0.347 to 1.53, from 0.013 to 0.048, from 0.126 to 0.556 and from 2.89 to 11.6 respectively and the average ratios were 0.037±0.017 for238Pu/239+240Pu, 0.357±0.040 for241Am/239+240Pu and 7.0±1.2 for90Sr/239+240Pu.

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Abstract  

A simple, sensitive and selective method is described for the simultaneous determination of plutonium and americium in lichen and moss samples which can be used as the atmospheric radioactivity bioindicators. Plutonium is separated from a HCl leaching solution by a Microthene-TNOA column; americium is separated by a KL-HDEHP column and purified by PMBP-TOPO extraction. A special attention has been paid to the decontamination of plutonium and americium from210Po. Ten lichen and 12 moss samples from tree trunks have been analyzed: starting from 2 g sample, the average yields and the detection limits were 70.2±12.5% and 28 mBq/kg for plutonium and 70.0±15.1% and 34 mBq/kg for americium. The concentrations (mBq/kg) ranged from 28 to 4960 for239,240Pu, from 28 to 171 for238Pu and from 34 to 1930 for241Am, respectively.

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Journal of Thermal Analysis and Calorimetry
Authors:
S. Montserrat
,
P. Colomer
,
Y. Calventus
,
F. López-Carrasquero
,
A. Ilarduya
, and
S. Muñoz-Guerra

Abstract  

A series of poly(α-n-alkyl β-L-aspartate)s (n being the number of carbon atoms in the linear alkyl side chain, withn=1, 2, 4, 6, 8, 12, 18 and 22), was studied by differential scanning calorimetry and thermogravimetric analysis. The effect of the length of the alkyl group on thermal properties such as stability, melting and crystallization of side chains, was investigated. For the polymers with n≥12, two endothermic peaks at T1 and T2 were detected separating three distinct phases A, B and C. The peak at T1 corresponds to the melting of the crystallized paraffinic side chains (transition A-B), and the peak: at T2 may be attributed to a transition (B-C), implying a liquid crystal phase.

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Abstract  

We have examined the uptake of actinide elements Am and, Pu by different species of lichen and moss collected in two locations (Urbino, Central Italy; Alps region, North-east Italy). Plutonium and americium were separated and determined by extraction chromatography, electrodeposition and alpha-spectrometry. This paper summarizes our results with a special emphasis on the vertical profiles of these actinides in two different species of mosses. Several 1–2 cm depth sections were obtained and dated by210Pb method. A typical peak for239,240Pu and241Am was found in the very old moss species (“Sphagnum Compactum”) at a depth corresponding to the period 1960–1970 which was the period characterized by the maximum nuclear weapon tests. In a younger moss species (“Neckeria Crispa”) no peak was observed and the regression curves showed that Am is more mobile than239,240Pu and238Pu.

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Abstract  

Separation chemistry plays an important role when alpha-and beta-emitting natural and artificial radionuclides at low levels must be determined in complex environmental matrices. This paper describes some separation techniques used in radioecology, with special emphasis on extraction chromatography. The very high necessary decontamination factors are pointed out together with the suggested techniques. The following examples are given: (a) determination of90Sr in soils in the presence of high concentration of210Bi; (b) determination of cosmogenic32P in sea water and its decontamination from234Th; (c) determination of63Ni and59Ni in liquid effluents; (d) separation techniques used for the speciation of plutonium in sea sediments and (e) plutonium and241Am concentration and vertical distribution in mosses.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
J. Santana Romero
,
F. Martínez Luzardo
,
E. Codorniú Hernández
,
L. Vargas Guerra
,
P. Melo Cala
,
M. García Guillén
,
K. Isaac Olivé
,
P. Estevez
,
A. Roque Córdoba
, and
M. Benítez

Abstract  

Vegetable tannins are polyphenolic plants secondary metabolites, widely distributed in all parts of trees and herbs. The role of these substances in many metabolic processes is very important. Vegetable tannins have been implicated as probable antinutritional factors, decreasing the assimilation of diet protein assimilation by cattle. On the other hand, protective antioxidant and antimutagenic properties have been ascribed for these compounds. Characterization of vegetable tannins is important in order to find new sources of natural raw materials with medical and pharmaceutical applications. Protein precipitation capacity as a function of pH, competitive protein and ADN binding assays and the determination of tannins concentration are described. Radioisotope labeled protein and tannins were used in all of the determinations.

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