University of Tasmania, Australia

Development of colorimetric binding phases for Diffusive Gradient in Thin-film - (DGT) passive sampling devices.

Diffusive gradient in thin-films (DGT) devices for sampling metals in the environment is a relatively recent technique developed by Davison et al. at Lancaster University to passively sample trace metals in-situ in water. The sampling technique relies on diffusion of metals under a concentration gradient across a diffusion layer with the metal then "fixed" in a binding phase. Although DGT devices have been extensively studied over the past decade many opportunities still exist for further development of the DGT sampling technique, including development of alternative binding phases. One such opportunity is the development of self-indicating metal chelating binding phases. To date we have developed binding phases that provide a colorimetric response to Cu(II), quantifiable using diffuse reflectance spectrometry or Computer Imaging Densitometry (CID) using a flat-bed scanner. This project will further develop DGT colorimetric binding phases by extending the technique to the sampling of metals such as Zn, Pb, Cd and Fe.