Evaluation of the Use of Anionic/ Nonionic Mixed Micelles in Reversed Phase Liquid Chromatography of Chlorophenols

The use of aqueous mixed micellar system consisting of sodium dodecyl sulfate (SDS) and polyoxyethylene (23) dodecanol (Brij-35) as the mobile phase in reversed-phase liquid chromatography was studied. A group of chlorophenols was used as the test mixture. Adding organic modifier to the system showed that the use of low concentrations of organic additives improves efficiency in SDS/Brij-35 mixed micellar mobile phase. The effects of propanol concentration, total surfactant concentration and pH upon retention and selectivity were also assessed. It was shown that a linear correlation exists between LnK′ and volume fraction of propanol over a range of 0-10%. Also, a regular decrease in solutes retention was observed as a function of surfactant concentration. The results showed that the elution strength increases as the mobile phase pH decreases. It was also revealed that the chromatographic selectivity changes with an increase in elution strength. * E-mail: [email protected] Introduction In the last two decades, the popularity of micellar liquid chromatography (MLC) as an alternative to reversed-phase liquid chromatography (RPLC) has increased. Micellar liquid chromatography has extended the capability of RPLC by allowing rapid gradient elution, detection sensitivity enhancement, unique separation selectivity, etc. [1-6]. The existence of solute-micelle interactions is a noticeable characteristic of micellar liquid chromatographic separations. In