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  • Author or Editor: J. de Goeij x
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Abstract  

Solid-phase extraction (SPE) cartridges with different functional groups(chelating, ion-exchange, hydrophobic) may be useful for copper speciationdeterminations of aqueous samples. Provided that each cartridge selectivelyextracts one species or a group of species, a fast screening of copper speciationcan be achieved by performing a series of extractions with different SPE cartridgesand combining the results. For this purpose, the performance of five SPE cartridgeswas studied with respect to extraction selectivity using samples with knowncomposition. Samples were spiked with a high-specific 64 Cu radiotracer toachieve easy detection of extracted copper species. Its high radioactivityper unit of mass ensures preservation of initial chemical equilibria and compositionof the sample. Results show that secondary interactions may take place onthe extracting phase when relatively clean samples are analyzed. Two naturalwater samples, viz. a ditch water and a seawater sample, were exposed to aseries of extractions as well. Species distributions found for these samplesgenerally correspond to expected distributions. Secondary interactions maybe suppressed in these cases, as other metal species compete for these interactions.

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Abstract  

The contribution of radiochemical neutron activation analysis (RCNAA) to trace-element analysis of biological materials in the last decades is outlined. Presently, the use of RCNAA is declining, since various powerful non-nuclear techniques for trace-element analysis have become available, strongly competing with RCNAA. This necessitates a re-evaluation of the position of RCNAA versus other analytical techniques for trace element analysis of biological materials. On the basis of the characteristic features of RCNAA and the capabilities of competing non-nuclear analytical techniques, possible future niches for RCNAA in the analytical market are indicated.

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Abstract  

A comparison of two group separation techniques using either NaI(Tl) or Ge(Li) spectrometry is presented for trace element determination in biological materials by neutron activation analysis. The capabilities of both procedures are described in terms of detection limits, precision and accuracy for the determination of the elements As, Cd, Co, Cr, Cu, Fe, Hg, Mo, Ni, Sb, Se, Sn, and Zn in various types of biological samples. For this purpose the (standard) reference materials NBS SRM-1577 Bovine Liver, Bowen's Kale, IAEA Pig Kidney H-7 and IAEA Milk Powder A-11 were analyzed. An attempt was also made to minimize blank values for several elements.

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Abstract  

An overview is presented of the characteristic features of RNAA (radiochemical neutron activation analysis). Criteria are given for comparison of RNAA with other trace-element analytical techniques. Appropriate fields of application of RNAA are indicated as well as approaches to secure the future position of the technique. Finally, some trends for further development of chemical separations in RNAA are outlined.

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Abstract  

The needs of continuation and extension of nuclear knowledge and expertise for science, technology, and the society as a whole are emphasized. Varios aspects of education and research in the nuclear field at the universities are discussed, as well as associated research facilities and expertise continuity measures.

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Abstract  

Thorium was determined in a liver autopsy sample from a person treated with Thorotrast ca. 40 y earlier. The decay products228Ac,224Ra,212Pb,212Bi, and208Tl from the232Th series were identified by direct -spectrometry. Instrumental neutron activation analysis yielded a value of ca 22 g thorium per kg dry liver material. The total radiation dose to the whole liver was estimated in the order of 16 Gy.

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Abstract  

Platmum levels have been determined in 145 samples from 24 tissues and 7 types of tumours from patients, treated with cisplatin. Sampled were 27 males (average age: 36 y, range: 22–63) and 19 females (average age: 52 y, range: 17–69), with an average total intravenous dose of 820 mg and 545 mg cisplatin, respectively. Samples were obtained via biopsy and autopsy, mostly 4–15 weeks after the last cisplatin administration. The long-term clearance of platinum from the tissues analyzed could be described by a first-order process with a half-life in the range of 175–300 days. The platinum fraction involved in the longterm total body clearance is estimated to be 22–38% of the total dose administered. However, the platinum clearance from a mature teratoma appeared to be much slower as measurable levels were detected 7.6 years after administration of the drug. The highest long-term platinum accumulations were found in liver, uterus, testes, ovary, and thyroid, and the lowest in brain and blood.

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Abstract  

An automated post-irradiation chemical separation scheme for the analysis of 14 trace elements in biological materials is described. The procedure consists of a destruction with sulfuric acid and hydrogen peroxide, a distillation of the volatile elements with hydrobromic acid and chromatography of both distillate and residue over Dowex 2X8 anion exchanger columns. Accuracy, precision and sensitivity are tested with reference materials (BOWEN’s kale, NBS bovine liver, IAEA materials dried animal whole blood, wheat flour, dried potatoes, powdered milk, oyster homogenate) and on a sample of pooled human blood. Blank values due to trace elements in the quartz irradiation vials are also discussed.

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Abstract  

In recent years increased information is required about the distribution of elements at low concentration levels in the biosphere. Neutron activation analysis can play an important role if it can supply many data at relatively low cost. As some of the concentrations are too low for determination by non-destructive techniques, equipment for chemical separations on a routine basis is necessary. For environmental studies a separation scheme has been developed successfully for arsenic, antimony, cadmium, copper, mercury, selenium and zinc. It is based on a combination of distillation and ion-exchange. Special attention is paid to the prevention of interference from bromine and sodium. Additional information about chromium, cobalt, nickel and tungsten can easily be obtained. Experience gathered with an automated instrument for fifty samples a week is described.

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Abstract  

Neutron activation analysis is attractive for trace-element determinations in large samples. Facilities for reactor irradiation and -ray spectrometry of kilogram-size cylindrical samples are described. The thermal neutron flux is ca. 5·1012m–2·s–1 with a th/ epi>104, so neutron self-thermalization can be neglected. The correction for the neutron attenuation within the sample is derived from measurement of the neutron flux depression just outside the sample. Correction for -attenuation in the sample is performed via linear attenuation coefficients derived via transmission measurements. Also the natural radioactivity in the sample is taken into account. Examples are given of materials to which large sample INAA has been applied successfully, and further lines of development and exploration are indicated.

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