Direct colorimetric detection of copper(II) ions in sampling using diffusive gradients in thin-films.
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.
School of Chemistry, University of Tasmania, Locked Bag 1371, Launceston, Tasmania 7250, Australia.
Russell W
RW
McGifford
Andrew J
AJ
Seen
Paul R
PR
Haddad
D000327:Adsorption; D000837:Anion Exchange Resins / Q000737:chemistry; D001979:Bromthymol Blue / Q000031:analogs & derivatives / Q000737:chemistry; D002413:Cations, Divalent / Q000032:analysis; D003124:Colorimetry / Q000379:methods*; D003300:Copper / Q000032:analysis*; D004058:Diffusion; D008567:Membranes, Artificial; D010316:Particle Size; D013499:Surface Properties
D000837:Anion Exchange Resins; D002413:Cations, Divalent; D008567:Membranes, Artificial; C002074:methylthymol blue; D003300:Copper; D001979:Bromthymol Blue