Exploring new DGT samplers containing a polymer inclusion membrane for mercury monitoring.

A polymer inclusion membrane (PIM) made of cellulose triacetate as a polymer and the task specific ionic liquid (IL) trioctylmethylammonium thiosalicylate (TOMATS) was assembled as a new Diffusive Gradients in Thin film (DGT) device to test its efficiency as a binding phase for mercury (Hg) monitoring. The effect of IL content was assessed, showing that higher TOMATS percentage is better for short deployment studies (up to hours), whereas for long-term exposure (up to days), a lower content can be more suitable. Different configurations of PIM-DGT samplers have been tested under controlled conditions and compared with in-house DGT conventional ones, manufactured with thiol groups as resin layer, for the determination of labile Hg. According to our results, a nonlinear accumulation profile of Hg with deployment time for the different designs of PIM-DGT was observed, limiting the range of applicability of the DGT technique. Promising results for the efficient removal of Hg from aqueous solutions and/or environmental monitoring studies were obtained with TOMATS.