Humic acids from oxidized coals : capillary zone electrophoresis and mass-spectrometry study.

Autor:	Praus, Petr, 1960-
Další autoři:	Klika, Zdeněk, 1943- Kurková, Monika Lourdes Pacheco, Ma. de
Jazyk:	angličtina
Předmět:	huminové kyseliny humic acids články journal articles oxidized coal capillary electrophoresis mass spectrometry
Druh dokumentu:	Non-fiction
ISSN:	1214-9705
Abstrakt:	Abstract: a1_Humic acids from open-air and laboratory oxidized bitumino us coals (under various temperatures) were prepared an d characterized. For the comparison, lignite and oxidized ligni te (oxihumolite) were examined as well. All samples were analyzed by capillary zone electrohoresis (CZE) and matr ix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF). For the CZE separation of humic acids (HAs), the borate-Tris-EDTA (pH=8.3) and borate-β-cyclodextrine (pH=9.6) electrolytes were used. The samples of humic acids were prepared by their dissoluti on in sodium hydroxide solutions. All CZE electropherograms are typical by a huge non-resolved peak (hump) which contains a lot of migrating humic acids. The ageing effect of HAs, brought about their self-assembling processes, was observed as a prolongation of hump migration times in both electrolyte systems. However, after 30 days a very good reproducibility of electropherogram s was obtained. In the borate-Tris-EDTA electrolyte the migration times of HAs relate to their metal (Pb) binding capacities. The broadening of the CZE humps of HAs, isolate d from laboratory oxidized bituminous coal, corresponds to their thermal decomposition during coal oxidation. Their shorter migration times were registered in the more alkaline borate-β-cyclodextrine electrolyte probably due to the further dissociation of HAs hydroxyl groups. In this electrolyte, the electrophoretic mobilities of HAs, isolated from lignite an d oxidized lignite, were significantly retarded likely due to the formation of inclusion complexes with β-cyclodextrine. By using the mass spectra of HAs isolated from laboratory and naturally oxidized coal it was found that the intensities of mass spectra lines are dependant on the temperature and amount of oxygen.
Databáze:	Katalog Knihovny AV ČR
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