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Determination of free copper concentrations in natural waters by using supported liquid membrane extraction under equilibrium conditions.

Authors
Type
Published Article
Journal
Analytical and bioanalytical chemistry
Publication Date
Volume
381
Issue
7
Pages
1452–1459
Identifiers
PMID: 15759138
Source
Medline
License
Unknown

Abstract

A method is described for measurement of freely dissolved copper concentrations in natural water samples using supported liquid membrane (SLM) extraction under equilibrium conditions, a technique denoted "equilibrium sampling through membranes" (ESTM). For this purpose, 1,10-dibenzyl-1,10-diaza-18-crown-6 as neutral carrier and oleic acid were used in the membrane phase. The main variables optimised were the carrier used to form the metal complexes, the organic solvent used in the membrane, the countercation, pH, the ligand used in the acceptor phase, the extraction time, and the flow rate of the donor phase. After the optimisation process an enrichment factor of 18.5 was obtained. Equilibrium conditions were reached after extraction for 60 min if a flow rate of 1.0 mL min(-1) or greater was used. When different ligands such as humic acids, phthalic acid, and EDTA were added to the sample solution, and sample pH ranged from 6 to 8, the results obtained for freely dissolved copper concentrations were in a good agreement with results from speciation calculations performed with Visual Minteq V 2.30, Cheaqs V L20.1, and WinHumic V. The developed technique was applied to analysis of stream and leachate water.

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