Amino acid solubilization in cationic reversed micelles: factors affectingamino acid and water transfer

The aim of this work is to investigate the driving forces involved in amino acid solubilization in cationic reversed micelles, and to determine in whi ch way different parameters affect the reversed micellar structure and amin o acid solubilization, in order to select the best conditions to optimize a mino acid extraction. To this end, extraction equilibrium experiments were performed using different experimental conditions and three amino acids wit h different structures: aspartic acid - a hydrophilic amino acid, phenylala nine - a slightly hydrophobic amino acid, and tryptophan - a hydrophobic am ino acid. The study of the effect of amino acid related parameters, such as pH and the initial amino acid concentration in the aqueous phase, and the effect of parameters that influence the reversed micellar structure, such a s surfactant concentration, ionic strength and co-surfactant concentration, provides useful information about the driving forces involved, solute-mice lle interfacial interactions and solute location in the cationic system tri octylmethylammonium chloride (TOIMAC)/hexanol/n-heptane. These parameters c an be adjusted to optimize amino acid extraction. It is shown that amino ac ids with the same isoelectric point can be selectively separated by explori ng the different interactions they establish with the reversed micellar int erface. (C) 1999 Society of Chemical Industry.