Dissolved iodide in marine waters determined with Diffusive Gradients in Thin-films technique

For the first time, Diffusive Gradient in Thin-films (DGT) focuses on inorganic iodine species iodate (IO3−) and iodide (I−). A silver-doped Cl resin (AgdCl), which is known to selectively accumulate I−, was used make a binding gel. Laboratory investigations were designed verify suitability of AgdCl-DGT method measure total I− concentration environmental waters. Total recovery obtained using an elution solution containing 100 mmol L−1 KCN. DGT validation experiments 10 NaCl showed linear accumulation over contrary IO3−, thus confirming selectivity AgdCl-binding The measurement independent pH (4.5–8.8) not impacted by presence bicarbonate (1–5 L−1). Finally, performance samplers tested two continental waters synthetic seawater. measured 27–33% up 24 h deployment whereas response retrieved seawater 72 (106 ± 7%). difference attributed low ionic strength waters, limiting application media with higher strength.