Influence of alcoholic modifiers on the selectivity of the separation of a group of polycyclic aromatic hydrocarbons by micellar liquid chromatography

The role of micelles and alcohols as the modifiers of the aqueous mobile phase in reversed-phase liquid chromatography in controlling retention and selectivity of polyaromatic hydrocarbons (PAHs) is studied. Elution strength increases with an increase in the alcohol or micelle concentration, and enhancement of separation selectivity with elution strength was observed. Increasing micelle concentration has an opposite effect, when compared to increasing alcohol modifier concentration, on the separation selectivity, showing that for this group of PAHs the separation selectivity is better with mobile phases of medium concentration of micelles and moderately high alcohol percentages. The selectivity enhancement can be explained in terms of the competing equilibria in micellar liquid chromatography.