Analytica Chimica Acta 2010-03-03

Direct colorimetric detection of copper(II) ions in sampling using diffusive gradients in thin-films.

Russell W McGifford, Andrew J Seen, Paul R Haddad

Index: Anal. Chim. Acta 662(1) , 44-50, (2010)

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Abstract

A novel binding phase was developed for use in diffusive gradients in thin-film (DGT) sampling for Cu(II) by employing methylthymol blue as a chelating and chromogenic agent. Methylthymol blue was adsorbed onto beads of Dowex 1 x 8 resin (200-400 mesh) and the resin beads were then immobilised onto an adhesive disc. Analysis of exposed binding discs by either UV-vis spectrophotometry or computer imaging densitometry provided robust quantification of adsorbed Cu(II) in the 0.2-1 microg cm(-2) range, allowing detection at microg L(-1) concentrations in the test solution (ca. 17 microg L(-1) for a 24 h deployment), and in good agreement with established DGT theory. The method was shown to be a potential replacement for binding phases based on Chelex 100 where a colorimetric response to a specific metal is desired.Copyright 2010 Elsevier B.V. All rights reserved.