Description of the partitioning behaviour of solutes and data treatment in micellar liquid chromatography with modifiers

The physico-chemical meaning of an empirical model, previously reported for describing the retention of solutes in reversed-phase liquid chromatography with micellar mobile phases of surfactant and alcohol, is given. The partition coefficient between stationary phase and water, and the solute-micelle association constant are considered as conditional parameters that depend on the concentration of modifier. An extension of the elution model is proposed for solutes having a strong hydrophobic character, that takes the strong interaction of these solutes with the stationary phase into account. Several fitting procedures (non-linear regression, and non-weighted and weighted linear regression) of the experimental data to the model are compared. The effect of errors in the value of the critical micellar concentration during the calculation of the retention physico-chemical parameters and prediction of the capacity factors, is also studied.