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Abstract  

A simple destructive neutron activation method for the determination of Hg and Se has been developed. The irradiated, sample is heated in a stream of oxygen at 1000°C, in a quartz tube in which two charcoal traps are positioned. The evaporated Hg, Se and contaminants such as Br are collected in the first charcoal trap. Only Hg is removed to the second trap by heating the first one at 750°C in a stream of nitrogen. The charcoal traps are them measured with a Ge(Li) detector. The analytical results obtained by this method for Hg and Se in several biological standard reference materials showed good agreement with the certified values.

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Abstract  

The thermal behavior of different synthesized polypyrrole (Ppy) composites was studied in order to obtain quantitative information about the synthesis process and qualitative information about thermal stability of composites. An inorganic anion has been used as dopant (PW12O40 3−), and this has allowed obtaining a complete analysis of Ppy degradation process, since this anion does not degrade in the range of temperature used. In order to validate the quantitative information obtained by thermogravimetric analysis (TG), the work was completed with X-ray photoelectron spectroscopy (XPS) study, since the use of the N+/N or W/N ratios are useful to measure the doping level reached by the synthesis process. Also pyrolysis/gas chromatography/mass spectrometry (py–GC–MS) and differential scanning calorimetry (DSC) were used to obtain information of the products generated as a consequence of the degradation process. FTIR-ATR has been used to characterize Ppy powders.

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