An Efficient Polymer Inclusion Membrane-Based Device for Cd Monitoring in Seawater

A novel and simple device that includes a polymer inclusion membrane (PIM) has been prepared and tested for the first time to detect low concentration levels of cadmium in seawater. The ionic liquid trihexyl (tetradecyl) phosphonium chloride (THTDPCl) has been shown to be an effective extractant when incorporated in a PIM that uses cellulose triacetate (CTA) as a polymer. However, it has been reported that the use of a plasticizer is mandatory to ensure an effective transport, which uses both ultrapure water and a nitric acid solution as a stripping phase. A special device incorporating a PIM made of 50% CTA, 40% nitrophenyl octyl ether (as a plasticizer), and 10% THTDPCl, effectively allows the quantitative transport and preconcentration of 10 µg L^-1 Cd from seawater samples to a stripping phase consisting of 0.5 M HNO₃ solution. This study shows that the efficiency of the PIM system is not affected by high salinity nor the presence of large amounts of other ions, and can thus facilitate Cd monitoring in seawater samples.