Ion-imprinted silica adsorbent modified diffusive gradients in thin films technique: Tool for speciation analysis of free lead species

A new diffusive gradients in thin films (DGT) device, using Pb(II) ion-imprinted silica (IIS) as the binding agents and commercial cellulose acetate dialysis (CAD) membrane as the diffusion layer (CAD/IIS-DGT), has been developed and evaluated for sampling and measurement of free Pb(II) species. The CAD/IIS-DGT devices were successfully applied to the measurement of free Pb(II) species in synthetic solutions, in natural freshwaters and in industrial wastewaters. The CAD/IIS-DGT provides reliable results over pH range of 4.5-6.5 and a wide range of ionic strength from 1.0×10(-3) to 0.7 mol L(-1). The concentrations of the free Pb(II) species in synthetic solution containing different concentrations of ligands measured by CAD/IIS-DGT showed a good agreement with the value measured by Pb-ion selective electrode. Field deployments of the CAD/IIS-DGT devices allowed accurate measurements of the concentrations of free Pb(II) species.