Speciation measurements with the permeation liquid membrane (PLM) technology require necessarily a good control of the flux of the analyte. In this perspective, a PLM-based multichannel flow-through cell has been designed. The first objective of this study has been to adapt the classical Levich model commonly used for electrochemical flow devices to the characteristic geometry of the PLM cell. In the latter case and contrary to the Levich model, the effects of the channel lateral walls on the flux of active species through the membrane have to be taken into account. The problem was solved by considering the existence of two parabolic Poiseuille profiles perpendicular to each other and developing along the fluid motion. The theoretical results obtained match satisfactorily with experimental data. The analytical study of this PLM system has been performed with copper(II) ions as test species and has shown that the preconcentration factor is (1) linear at least for preconcentration times of < or = 120 min, (2) reproducible on the same membrane as well as on different membranes, and (3) independent of the initial test metal ion concentration in the sample solution. The capabilities of this cell to determine metal speciation by considering lability of complexes and the flux of metal at variable flow rates of the test solution is also discussed by means of Cu(II)/sulfosalicylic complexes.

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The assisted transfer of silver ion, Ag + , by complexation of Ag + with the tetrakis(4-chlorophenyl)borate (TPBCl − ) anion was studied at the interface between two immiscible electrolyte solutions (ITIES).The elucidation of the interfacial mechanisms employed the cyclic voltammetry technique applied to macro and micro liquid/liquid interfaces. This procedure allowed to identify Ag + as the species which is transferred at the liquid/liquid interface and also the formation of an 1:2 metal:ligand complex when TPBCl − is in excess. The value for the formal transfer potential of silver(I) from aqueous to 1,2-dichloroethane was evaluated and the association constant for the [Ag(TPBCl) 2 ]− complex was determined.

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