Document Detail

Determination of the total concentration and speciation of Al(III) in tea infusions.
MedLine Citation:
PMID:  14507463     Owner:  NLM     Status:  MEDLINE    
The aluminium species in different tea infusions were investigated, by determining their stability constants and concentration. This was done for some particular samples using a simple experimental method based on the sorption of aluminium on the strongly sorbing resin Chelex 100, by a batch procedure. From the thermodynamic information obtained it is possible to calculate the concentration of the different species, and in particular that of the free metal ion, which is very important for evaluating the adsorption of aluminium on biological membranes. It was found that aluminium in the tea infusions here considered is present at high total concentration, approximately 0.1 mM, but mainly linked to strong complexes, for instance with side reaction coefficient higher than 10(5.11) at pH 3.95 in one case (tea 1). This could be the reason for the low toxicity of aluminium in tea. These strong complexes were not dissociated even in the presence of Chelex 100. In this case only a limiting value of the reaction coefficient could be evaluated. The presence of the very strong complexes was found in all the tea sample here considered. In two of the considered samples (one black and one green tea) a part of Al(III) was linked to less strong complexes, for example with a reaction coefficient 10(4.14) (tea 2, pH 4.20). The presence in the considered tea infusions of other substances able to complex aluminium was also detected, by the well known ligand titration procedure, at concentration ranging from 0.65 to 3.37 mM in three tea infusions, and at somewhat higher concentration in the case of the ready drink, which was also considered for comparison.
Giancarla Alberti; Raffaela Biesuz; Antonella Profumo; Maria Pesavento
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of inorganic biochemistry     Volume:  97     ISSN:  0162-0134     ISO Abbreviation:  J. Inorg. Biochem.     Publication Date:  2003 Sep 
Date Detail:
Created Date:  2003-09-25     Completed Date:  2003-11-26     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  7905788     Medline TA:  J Inorg Biochem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  79-88     Citation Subset:  IM    
Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy.
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MeSH Terms
Aluminum / analysis*,  chemistry*,  toxicity
Cation Exchange Resins / metabolism
Cations / analysis,  chemistry
Chelating Agents / metabolism
Hydrogen-Ion Concentration
Phenols / analysis
Sucrose / chemistry
Tea / chemistry*
Reg. No./Substance:
0/Cation Exchange Resins; 0/Cations; 0/Chelating Agents; 0/Phenols; 0/Tea; 57-50-1/Sucrose; 7429-90-5/Aluminum

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