Comparison of an empirical and a theoretical linear solvation energy relationship applied to the characterization of solute distribution in a poly(ethylene) glycol-salt aqueous biphasic system

A Linear Solvation Energy Relationship (LSER) developed by Abraham has been applied to the partition of organic solutes in an Aqueous Biphasic System (ABS) and to published values of their 1-octanol/water partition coefficients. The results are compared to the application of a conceptually similar Theoretical Linear Solvation Energy Relationship (TLSER) developed by Famini and co-workers. Differences and similarities in the molecular properties highlighted by each LSER are discussed. The theoretical relationship of Famini, although modeled on the approach of Abraham, seems not to encapsulate molecular properties in the same way as the Abraham's empirical relationship. However, this theoretical approach has the great merit of computational simplicity, and it is concluded that efforts directed toward its improvement could be rewarding.