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  • Author or Editor: Z. Samczyński x
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Abstract  

A method for the determination of cadmium and zinc in geological and environmental materials by radiochemical neutron activation analysis is presented. It is based on the isolation of the analytes using the amphoteric ion exchange resin Retardion 11A8. The elaborated ion exchange procedure is accomplished both before and after neutron activation. Depending on the eluent composition Retardion 11A8 acts as an anion or a cation exchanger. The method was tested by determining Cd and Zn in two reference materials: Lake Sediment (SL-1) and Zinnwaldite ZW-C. The results of quantitative determinations show good agreement with the certified values.

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Abstract  

A new method for the selective radiochemical separation of cadmium from other elements, present in biological materials, using amphoteric ion exchange resin Retardion 11A8 has been elaborated. Cadmium can be taken up by the resin either as anionic chloride complexes or cationic ammine complexes, depending on the composition of the eluent, exploiting both cation and anion exchange functions of the ion exchanger. The conditions in which Cd is quantitatively retained and eluted from Retardion 11A8 were established. The method of selective isolation of cadmium was further used for the determination of Cd in three biological certified reference materials by neutron activation analysis. Analytical results obtained with the use of the proposed separation procedure show good agreement with the certified values.

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Abstract  

A new method has been developed aimed at determining traces of lanthanides in the materials of biological origin by NAA. The chemical procedure that involves both, selective and quantitative pre-irradiation isolation of the elements of interest and post-irradiation separation of lanthanides into two groups has been employed. The method is based on classical column ion-exchange and extraction chromatography. In the pre-irradiation step all the accompanying elements are eliminated and the quantitatively isolated lanthanides fraction is free from highly activating macro components, as well as from other trace elements, including uranium, which is the source of spectral and nuclear interferences. After neutron irradiation, the lanthanide fraction is divided into two sub-fractions, taking advantage of the different anion-exchange affinities of individual lanthanide complexes with EDTA towards strongly basic anion-exchanger. This provides the favorable gamma-ray spectrometric measurement conditions enabling reliable determination of 13 elements.

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Abstract  

Preparation and characterization of two new reference materials of biological origin, namely: Tea Leaves (INCT-TL-1) and Mixed Polish Herbs (INCT-MPH-2) is described. The raw materials were ground in an agate ball mill, sieved through a nylon sieve, collecting fraction of particle size: Æ£67 ·m, and carefully homogenized. Preliminary homogeneity testing by XRF method and final checking of homogeneity by NAA after distribution of the materials into containers revealed that they are sufficiently homogeneous at least for sample size ≥100 mg. Both materials were prepared in amounts exceeding 40 kg and certified on the basis of a worldwide interlaboratory comparison, in which 109 laboratories from 19 countries participated. The method of data evaluation leading to assignment of certified values was essentially the same as that used previously in this Laboratory, but supplemented by additional data from the analysis of a CRM which was sent to the participants and analyzed by them along with the candidate reference materials. In addition the results for a few elements by very accurate developed methods in this Laboratory were obtained and used to support the certification process. Analytical uncertainties and stability uncertainties were quantified to arrive at combined uncertainties of the certified values. So far 18 elements in INCT-TL-1 and 21 in INCT-MPH-2 could be certified.

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