Amino acid solubilization in cationic reversed micelles: Factors affecting amino 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 which way different parameters affect the reversed micellar structure and amino acid solubilization, in order to select the best conditions to optimize amino acid extraction. To this end, extraction equilibrium experiments were performed using different experimental conditions and three amino acids with different structures: aspartic acid - a hydrophilic amino acid, phenylalanine - a slightly hydrophobic amino acid, and tryptophan - a hydrophobic amino 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 as surfactant concentration, ionic strength and co-surfactant concentration, provides useful information about the driving forces involved, solute-micelle interfacial interactions and solute location in the cationic system trioctylmethylammonium chloride (TOMAC)I hexanol/n-heptane. These parameters can be adjusted to optimize amino acid extraction. It is shown that amino acids with the same isoelectric point can be selectively separated by exploring the different interactions they establish with the reversed micellar interface.