THEORETICAL ASPECTS OF MICELLAR LIQUID-CHROMATOGRAPHY USING C(12)DAPSSURFACTANT

Theoretical aspects of micellar liquid chromatography using a zwitteri onic 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 mu Bo ndapak C-18 column, UV detection was measured at 254 nm. Using the Arm strong equation, the partition equilibria constants of the solutes chr omatographied were established between water and stationary phase; wat er 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 surfact ant concentration, capacity factors are greater on C(12)DAPS. Hydropho bic interactions with the stationary phase, electrostatic effects of t he surfactant from both the micelle and the surfactant modified statio nary phase explain the retention of a solute. An other way to study mo lecular interactions is made via the linear solvation energy relations hips (LSER). For the test solutes used, it seems that V-1/100 (solute' s size) and beta (basicity) are predominant to affect the retention. K -SW LSER correlation express the binding of the solute with the micell es. The term s found is positive. C(12)DAPS has a greater dipolar envi ronment affecting considerably the MLC partition. The term a is positi ve, acidic solutes binds more easily with the zwitterionic surfactant than with SDS. (C) 1998 Elsevier Science B.V. All rights reserved.