Theoretical aspects of micellar liquid chromatography using C12DAPS surfactant

Abstract Theoretical aspects of micellar liquid chromatography using a zwitterionic surfactant were investigated. The micellar mobile phase consisted of n -dodecyl- N , N -Dimethylamino-3-propane-1-sulfonate (better known as C 12 DAPS) aqueous solutions. Chromatography was carried out on μ Bondapak C 18 column, UV detection was measured at 254 nm. Using the Armstrong equation, the partition equilibria constants of the solutes chromatographied were established between water and stationary phase; water and micelles; micelles and stationary phase. Compared to anionic or cationic surfactants, the zwitterionic surfactant gives the highest K SW values and a lowest K MW values. Therefore, for a constant surfactant concentration, capacity factors are greater on C 12 DAPS. Hydrophobic interactions with the stationary phase, electrostatic effects of the surfactant from both the micelle and the surfactant modified stationary phase explain the retention of a solute. An other way to study molecular interactions is made via the linear solvation energy relationships (LSER). For the test solutes used, it seems that V 1 /100 (solute's size) and β (basicity) are predominant to affect the retention. K SW LSER correlation express the binding of the solute with the micelles. The term s found is positive. C 12 DAPS has a greater dipolar environment affecting considerably the MLC partition. The term a is positive, acidic solutes binds more easily with the zwitterionic surfactant than with SDS.