Linear Solvation Energy Relationships (LSERs) are used to explain the congeneric behavior observed when using Micellar Electrokinetic Chromatography (MEKC) to estimate the octanol-water partition coefficient scale of solute hydrophobicity. Such studies provide useful insights about the nature of solute interactions that are responsible for the sources of congeneric relationships between MEKC retention and log Po/w. It was determined that solute dipolarity/polarizability and hydrogen-bonding character play the most important roles in the congeneric behavior observed for many surfactant systems. The individual dipolarity/polarizability and hydrogen-bonding contributions to the free energy of transfer were also investigated.

A mixture of a tri‐block copolymer, poly(methyl methacrylate‐ethyl acrylate‐methacrylic acid), commercially known as Elvacite 2669, and sodium dodecyl sulfate (SDS) micelle was investigated as pseudo‐stationary phase in Micellar Electrokinetic Chromatography (MEKC). The properties of the mixed system were characterized using surface tension and conductance experiments, as well as absorbance and fluorescence solvatochromic studies using ET(30) and pyrene as the probes. In this mixed system the SDS has a critical micelle concentration of 2 mM and the fluorescence data indicates that it has a microenvironment similar to SDS alone. Additionally, the solvation properties of the individual and the mixed systems were compared using linear solvation energy relationships (LSER). As compared to the SDS micelles, the mixed pseudo‐phase is a weaker hydrogen bond donor and has stronger polarizability properties. The functional group selectivities in the mixed pseudo phase are different from that in the SDS micelle. The functional group selectivities of non‐hydrogen bonding and hydrogen bonding solutes provide further support for the LSER findings.