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Dynamic Modelling of Nickel Complexation in Xylem Sap of Quercus ilex : A Voltammetric Study
Author(s) -
dos Santos Margarida Maria Correia,
Alves Sheila,
de Lurdes SimõesGonçalves Maria,
Nabais Cristina
Publication year - 2006
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200503446
Subject(s) - xylem , chemistry , nickel , hanging mercury drop electrode , ionic strength , cyclic voltammetry , mercury (programming language) , voltammetry , kinetics , inorganic chemistry , oxalic acid , nuclear chemistry , electrode , electrochemistry , botany , organic chemistry , physics , quantum mechanics , aqueous solution , computer science , biology , programming language
Holm oak ( Quercus ilex ) is the dominant tree growing on serpentine soils of northeast Portugal, characterized by elevated soil concentrations of Ni and Mg, combined with low Ca concentrations. Apparently Q. ilex does not suffer from excessive concentrations of Ni in the soil. In this work we report a complexation study of nickel by the relevant ligands present in xylem sap: histidine, aspartic acid, oxalic and citric acids, at 0.10 M ionic strength and pH 5.5. Single and mixed complexes were characterized. To validate the proposed complexation model, diluted solutions of Q. ilex xylem sap were titrated with nickel. All studies were done using square‐wave voltammetry (SWV) at a hanging mercury drop electrode. Due to the dynamic nature of SWV, it is possible to obtain the conditional stability constants of the complexes formed but also to have knowledge on the kinetics of the interconversion of the species present.