RESUMO
This paper presents for the first time a phenomenological theoretical model for the time dependent distribution of analytes during electromembrane extraction (EME). The model was verified experimentally for a range of model drugs and peptides. Analytes were extracted from an acidified aqueous sample solution, through an organic supported liquid membrane (SLM), and into an acidified aqueous acceptor solution. Mass transfer was governed by an applied electric field across the SLM. A rapid depletion was seen in the sample during extractions, with a steady increase in the amount accumulated in the acceptor solution. This was in good accordance with the theoretical model. A deviation from the modeled behavior was seen for some of the peptides where trapping of analyte in the SLM was high. The results demonstrated for the first time that EME behaved like a distribution system, with voltage dependent distribution coefficients. In addition, electrokinetic migration was observed across the SLM, which added an electrophoretic component to the mass transfer. This improved theoretical understanding will be highly beneficial for future optimization and development of applications using EME.