A charged organic-inorganic nanofiltration (NF) membrane prototype was used to separate a mixture of nine amino acids (AA) on the basis of differential electrostatic interactions with the membrane because, for a given pH, some of them were positively charged, some were negative, and some were zwitte
Effect of physicochemical parameters on trace inorganic selenium stability
✍ Scribed by M.G. Cobo; M.A. Palacios; C. Cámara; F. Reis; Ph. Quevauviller
- Book ID
- 102981263
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 755 KB
- Volume
- 286
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
The stability of Se(W) and SeWI) species at 10 and 50 ng ml-' concentrations, at different pH values, in the presence or absence of chloride and stored at different temperatures and in different containers was reported. Se(W) was determined by hydride generation atomic absorption spectrometry (HG-AAS) and SeWI) by reducing Se(W) to Se(IV) and calculating the difference between total inorganic Se and Se(W). Neutron activation analysis (NAA) was used for quality control. Complete loss of Se(W) occurred after twelve months when samples were stored in polyethylene containers at pH 2 in the absence and in the presence of chloride. Se(W) was stable under those conditions for the twelve months tested. The stability of Se(W) increased at pH 6, with two months being the maximum storage time without risk of Se0V) loss. The presence of Cl-decreased the risk of losses in mrne cases. FTFE containers increased SeXIV) losses at pH 6, especially at 10 ng ml-'. Both species were stable at -20°C for the twelve months tested and losses of Se(W) and Se(W) were lower at 40°C than at room temperature. A discussion of these results and data published in the literature are included in this paper.
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