Solute-solvent interactions in micellar electrokinetic chromatography - Selectivity of lithium dodecyl sulfate-lithium perfluorooctanesulfonate mixed-micellar buffers

The solvation parameter model has been applied to the characterization of m icellar electrokinetic chromatographic (MEKC) systems with mixtures of lith ium dodecyl sulfate and lithium perfluorooctanesulfonate as surfactant. The variation in MEKC surfactant composition results in changes in the coeffic ients of the correlation equation, which in turns leads to information on s olute-solvent and solute-micelle interactions. Lithium perfluorooctanesulfo nate is more dipolar and hydrogen bond acidic but less polarizable and hydr ogen bond basic than lithium dodecyl sulfate. Therefore mixtures of lithium dodecyl sulfate and lithium perfluorooctanesulfonate cover a very wide ran ge of polarity and hydrogen bond properties, which in turn results in impor tant selectivity changes for analytes with different solute properties. (C) 2001 Elsevier Science B.V. All rights reserved.