Chromatographic behavior of polar compounds in the transition between reversed-phase and submicellar/micellar liquid chromatography

Micellar liquid chromatography (MLC) is a reversed-phase liquid chromatography (RPLC) mode employing a surfactant, typically sodium dodecyl sulfate (SDS), which is biodegradable, in an aqueous or aqueous-organic mobile phase above its critical micellar concentration (CMC). Under these conditions, substantial alterations in retention, selectivity and peak profile occur in comparison to RPLC using conventional hydro-organic mobile phases. These changes arise from the presence of micelles in the mobile phase and the adsorption of surfactant on the stationary phase. In this work, the chromatographic performance of polar compounds of diverse nature is investigated using mobile phases containing SDS below and above its CMC in the presence of acetonitrile. Three nucleosides, four diuretics, and four sulfonamides, all of biomedical and pharmaceutical significance and possessing distinct acid-base characteristics, were chosen as probe compounds. Modifications in retention and peak shape were investigated using experimental conditions that enable the transition from submicellar to micellar conditions. A comparison was also made with conventional RPLC. Analysing the polar compounds with RPLC under low submicellar or micellar conditions significantly decreases the consumption of organic solvent in comparison to hydrophilic liquid chromatography (HILIC).