X-ray fluorescence in IAEA Member States: Argentina

Full text: The following projects carried out by the XRF Group are described: 1. Iridium Detection by Total Reflection x-Ray Fluorescence in Samples Providing from The Cretaceous-Tertiary Boundary and Experimental Amphibian Embryos - The main purpose of this study is to report the high sensitivity of TXRF for Ir measurements in mineral and biological samples. Mineral samples originate from different horizon deposits in the Neuquen basin, Argentina. Ir anomaly seems to be related to diderophite material provided to Earth in large quantities most probably by a 10 km asteroid that impacted earth 65 Myears ago. Sample preparation procedures and multielemental information are available. In a particular case of amphibian embryos, the detected level of Ir was in the order of 1 part per million (bioconcentration factor of 9). 2. Polymer Solutions on Glass: Adsorption Study by Total Reflection x-Ray Fluorescence - Equilibrium properties of a polymer solution in the vicinity of a solid-liquid interface are locally altered relative to the properties in bulk. This is caused probably by attractive or repulsive interactions adsorbed fraction-adsorbent. In this way, theoretical models for flexible and rod-like polymers were published.The present work is related to study of the adsorption of 0 to 0.05% aqueous scleroglucan solution on 400 to 600 μm glass microspheres. This study was possible by labeling the macromolecule by means of a chemical reaction with iodine, and then detecting by TXRF. Results show that for dilute concentration polymers behave in an anomalous way near the interface, contrary to the previous theoretical predictions. A first attempt to explain this behavior is presented. 3. Total Reflection x-Ray Fluorescence Polymer Spectra: Classification By Taxonomy Statistic Tools - The aim of this work is to explore the use of chemometric tools for the classification of synthetic and natural polymers with a mean molecular weight greater than 106. Spectra obtained by TXRF technique were analysed in order to retrieve matrix information and to illustrate calibration procedure. The intensities of coherent and incoherent scattered peaks were selected for this purpose. The investigated polymers were aqueous solution of scleroglucan, polyacrilamide, polyoxyethylene oxide, glucomannan, 2,3,6-tri-o-ethylamylose and xhantan, between 0 to 1% (m/m) concentration range. MATLAB software is used for numerical calculations. Using a combination of principal component analysis and cluster analysis, the differences in composition of various analyzed polymers can be visualised. 4. Sampling extended areas: planning analytical protocols - This project describes a methodology for sampling large areas taking into account QA and QC requirements (to ensure representativeness of samples). The proposed methodology offers a general approach to planning field investigations that could be useful for any type of environmental studies. In a report we describe the criteria for sampling planning, sampling protocols checklist, sampling devices, transportation and blank sample requirements. The final objective is to design a sampling strategy that will eventually allow the use of portable EDXRF instruments for in situ analysis of soil. This methodology will be applied for soil characterization in the zone of Campana, Argentina, by evaluating data coming from an EDXRF spectrometer with a radioisotope excitation. The samples were obtained from two different layers: A) the top soil (0-15 cm depth) and B) at 50-60 cm, covering an area of approximately 80 km2. (author)