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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 371010
Title Stability of lead(II) complexes of alginate oligomers
Author(s) Davis, T.A.; Pinheiro, J.P.; Grasdalen, H.; Smidsrod, O.; Leeuwen, H.P. van
Source Environmental Science and Technology 42 (2008)5. - ISSN 0013-936X - p. 1673 - 1679.
Department(s) Physical Chemistry and Colloid Science
Publication type Refereed Article in a scientific journal
Publication year 2008
Keyword(s) metal speciation analysis - x-ray-diffraction - l-guluronic acid - bacillus-subtilis - cell-walls - stripping chronopotentiometry - heavy-metals - structural components - crystalline-structure - ionic-strength
Abstract The current work reports on the Pb(II) complexes formed with oligomeric uronic acids (carboxylated saccharide residues) found polymerized in the cell walls and envelopes of algae and bacteria alike. The application of partial acid hydrolysis, size-exclusion chromatography (SEC), 1H NMR, and scanned deposition stripping chronopotentiometry (SSCP) has permitted the determination of stability constants for Pb(II) with both mannuronic (M) and guluronic (G) acid oligomers ranging from the dimer to the pentamer. The determined logarithm of the stability constants range between 4.11 ± 0.05 and 5.00 ± 0.04 mol¿1·dm3 for the eight oligomers studied (pH 6; I = 0.1 mol·dm¿3). Additional experiments under the same experimental conditions employing galacturonic and glucuronic acid oligomers yielded slightly lower values (2.19 ± 0.10 to 4.02 ± 0.07 mol¿1·dm3) that were expected based on their structure, whereby the monomers which were not included in the alginate oligomer series (unavailable by SEC), yielded the lowest stability constants. This work demonstrates the applicability of the SSCP technique for the determination of stability constants for metal¿ligand complexes in which the ligands display relatively low molecular mass. Previous studies on heavy metal interaction with the matrix polysaccharide alginate have largely been restricted to the whole polymer that forms a gel upon binding to network bridging ions such as calcium. The results will be discussed in this context with the emphasis being placed on the relevance of these findings to processes occurring at the biointerface and results from the relevant literature.
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