Diffusive Gradients in Thin Films (DGT) Methodology for Selective and Spatially Discriminating Binding of Metal Ions

We are currently trialling the technique in the lab and will conduct field trials in the Derwent Estuary. Taken from the abstract of the referenced paper: 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 1x8 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 micro gcm-2 range, allowing detection at micro gL-1 concentrations in the test solution (ca. 17 micro gL-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.