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Abstract  

A sensitive, rapid and selective method for the determination of237Np in urine is described. Neptunium(IV) is isolated by batch-extraction with a slurry of Microthene-710 (microporous polyethylene) supporting a cyclohexane solution of tri-n-octylphosphine oxide, the slurry is transferred into a column and neptunium eluted by oxidation to Np(V) with a mixture of HCl+Cl2. After electroplating on a stainless steel disc, neptunium is counted with a solid-state alpha-detector. The final recovery is 83.2%; the decontamination factors are sufficiently high and the sensitivity limit is suitable for radiotoxicological purposes.

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Abstract  

The paper describes the application of extraction chromatography to the determination of several alpha and beta emitters in biological and environmental samples. Both column extraction chromatography and batch extraction process have been used to isolate the radionuclides from the samples. The effect of several parameters (extractant concentration, support granulometry, stirring time, temperature, presence of a complexing agent) on the extraction and elution has been examined. The application of redox extraction chromatography is also described.

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Abstract  

The paper describes the radiochemical and chemical analyses of industrial graphite scraps showing high radioactivity levels. The uranium concentration in some graphite scraps was very high (up to l kBq/g, 7.7%w/w) and its distribution greatly heterogeneus. Some uranium solubility tests carried out on the graphite scraps showed that 60–70% of the element could be dissolved with a buffer solution at pH 4 and that complete dissolution could be obtained by leaching with conc. HNO3 . By taking into account these results it can be concluded that the radioactive contaminant consists of uranium chemically purified and isotopically treated.

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Abstract  

During the last 14 years the Radioecology Laboratory of Parma University and the General Chemistry Institute of Urbino University collaborated on a radioecological programme having the aim to observe the evolution of antropogenic radioactivity in Antarctica in the period 1987-2001. The artificial radionuclides considered were 90Sr, 137Cs, 239+240Pu,238Pu and 241Am. The contamination seems to be higher in the continental environment rather than in the marine one. Mosses, algae and lichens showed the highest values for all radionuclides analyzed. The results prove that the Antarctic continent is interested by radioactive pollution. As far as 137Cs is concerned, a progressive decrease was observed.

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Abstract  

Suitable separation techniques were prepared for actinide,90Sr and226Ra determinations in environmental and industrial samples. Extraction chromatography with tri-n-octylphosphine oxide (TOPO) and di(2-ethylhexyl) phosphoric acid (HDEHP) solutions was used. IN some cases, a powder of Microthene (Microporous polyethylene) supporting solid TOPO was prepared thus obtaining a material showing better storing and column preparation features.Uranium and226Ra were determined in phosphorites, phosphoric acid and phosphogypsum.Uranium, thorium and226Ra were also measured in the low specific activity scales of hydrocarbon production equipment:226Ra was found to concentrate in some parts of the plant so causing a radiation protection problem.Plutonium and90Sr were measured either in some Mediterranean Sea samples or in environmental samples collected in Antarctica. Some interesting sea sediment profiles were also obtained.All the chemical methods were verified by: a) adding some yield tracers (232U,228Th,242Pu); b) analyzing some certified samples supplied by IAEA and NIST; c) participating in some international intercomparison runs; d) using, when possible, both an analytical and a radiometric method and e) following the radioactivity decay or growth (90Y and226Ra).

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Abstract  

This paper describes a method for the determination of gross -activity (actinides) in urine. The method consists of a coprecipitation of actinides as Fe/Ca phosphates and hydroxides, a purification as iron phosphate and a LaF3 source preparation; -spectrometry is then carried out without any electroplating procedure. The average recoveries of the method for actinides (except uranium) were about 83.8±8.1%. With a counting time of 1440 min and a counting efficiency of 38% the detection limit was 0.25 mBq/l (6.8 fCi/l). The gross -activity in urine blanks ranged from 0.35 to 0.80 mBq/l (9.4 to 22 fCi/l).

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Abstract  

An extraction chromatography method with a column of microporous polyethylene supporting tri-n-octylamine /TNOA/ was used to separate uranium and thorium from zircon sands. The two elements were determined both by physical-chemical techniques /fluorimetry and colorimetry/ and by radiometric techniques /alpha spectrometry/ after electrodeposition: their respective contents agreed well; furthermore, uranium and thorium isotopes resulted in secular equilibrium in the analyzed material.

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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  

An extraction chromatographic method based on microporous polyethylene (Microthene) supporting tri-n-octylphosphine oxide (TOPO) was used to separate uranium and226Ra from phosphorites and their industrial derivatives. Uranium was then determined by fluorimetry and by alpha-spectrometry after electroplating, and radium by precipitation as Ba(Ra)SO4 and alpha counting with a ZnS(Ag) alpha detector. The method was checked by using an IAEA phosphorite sample having a certified uranium concentration. Some phosphorite, phosphoric acid and plaster samples supplied by an Italian industrial plant were analyzed; uranium isotopes always resulted in radioactive secular equilibrium.

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