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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.

The extraction of divalent transition metals (M = Cu, Zn, Co, Cd) with mixtures of 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HL) and crown-ethers (E = B15C5, 18C6, DC18C6, DB18C6, DC24C8, DB24C8 with B = benzo, DB = dibenzo, DC = dicyclohexyl) in chloroform has been studied. From 1.0 M K+ aqueous solutions, EK.ML, ion pairs have been extracted with 18C6 -type crown ether3 that have a good correspondence between their cavity size and the K+ diameter, -and with M = CO and Cd, metals with a higher stability of the ML anion. With B15C5, which has a cavity size too small to accoddate K+, the synergic extraction of Co is explained by the formation of E K.CoL Both CoL2E and EBa(CoL l2 (E = DB18C6)were extracted frgm 0.h~ Ba(N0 l . In all otAer experiments -extractions from 1 .OM LiC1, ~a~l ! t?a~0~ with 815C5, 1.On leave from Escola Tecnica Superior dtEnginyers Industrials de Barcelone (U.P.C.) Diagonal 649, 08028 Barcelona (Spains). SASTRE ET AL.18C6 and 24C8 -type crown ethers, extractions from 1.0 -M KC1 with DB24~8, extractions from 0.33M Ba(N0 1 2 . with B15C5 and -DB24C8 -only MLZE species were extractedl with a negligible influence of the crown ether cavity size. No synergic extraction of copper was observed regardless of the crown ether and the aqueous electrolyte.

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