Transport between an aqueous phase and a CTAB/hexanol-octane reversed micellar phase

Using bovine serum albumin (BSA) as a model protein, protein transport betw een an aqueous phase and a reversed micellar organic phase was examined. Fr om near-infrared spectra and UV absorption spectra, it was confirmed that C TAB (cetyl trimethyl ammonium bromide)/hexanol-octane reversed micellar sol ution is a suitable medium for BSA solubilization. It seems that the forwar d transfer efficiency depends not only on the parameters of the two phases (for example: the pH value, the concentration and species of ions in the aq ueous phase, the content of surfactant and co-solvent in reversed micellar solution), but also the titration behaviour and the concentration of the pr otein in aqueous phase. The experimental results lead to the conclusion tha t the major driving force in the protein extraction is electrostatic intera ction. A modified phenomenological thermodynamic model for reversed micella r extraction was presented, and shown to correlate the data on extraction e fficiency of BSA with both pH value and surfactant concentration. The effec ts of various factors, such as pH, and the type and concentration of salt i n stripping solution, on BSA back transfer were also studied. It was found that the backward transfer efficiency of BSA is strongly influenced by the type of ions in stripping solution. When the operation runs under optimized conditions and with suitable phase ratio, the recovery and concentration o f protein were successfully obtained: In addition, the problems how long th e reversed micellar solutions can be recycled and how much of the surfactan t will be lost to the aqueous phase have been examined. (C) 1998 Elsevier S cience S.A.