AOT REVERSED MICELLES AS CARRIERS OF AMINO-ACIDS ACROSS LIQUID MEMBRANES - SEARCH FOR SELECTIVITY AND CHIRALITY EFFECT

Reversed micelles of diethylhexyl sodium sulphosuccinate (AOT) are use d in this work as mobile carriers to transport amino acids between a s ource (S) and a receiving (R) aqueous phase across an organic liquid m embrane (M) (iso-octane). For most experiments the aqueous and organic phases were those of a pre-equilibrated Winsor II system. Semipermeab le membranes have been introduced between the S and M phases as well a s between the M and R phases for technical reasons. The rates of trans port of p-iodophenylalanine and tryptophan were compared and discussed in relation to their partition coefficients between water and the AOT palisade layer, showing completely different behaviour between the tw o amino acids. As the selectivity of the transport process may depend on the water content of the membrane phase and also on the carrier/sol ute interactions, we have investigated the rate of water uptake by the AOT reversed micelles as well as the influence of the ionization stat e of amino acids. The last part of the work is concerned with an attem pt to perform enantioselective transports using chiral AOT. The analys is of the receiving phase required in that case a chromatographic reso lution of amino acid enantiomers. This resolution was affected by the nature of the background salt, which had to be specifically adapted fo r this purpose. The failure of these experiments in producing enantiom eric enrichments suggests that the rigidity of the surfactant film is not sufficient to permit chiral recognition in that case.