Zeitschrift für Chromatographie und Trenntechniken
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Estimation of Octanol-Water Partition Coefficient Using Cationic Gemini Surfactants by Micellar Electrokinetic Chromatography

Mustafa GUZEL, Cevdet AKBAY, Yatzka HOYOS and David H. AHLSTROM

Micellar electrokinetic chromatography (MEKC) provides a simple and rapid approach for determining n-octanolwater partition coefficients (log Pow). A set of non-hydrogen bonding (NHB), hydrogen bond accepting (HBA) and hydrogen bond donating (HBD) benzene derivatives with known log Pow values was used as sample solutes. Two novel cationic gemini surfactants with different head groups were used as pseudostationary phases. Sodium dodecyl sulfate (SDS) was also used for comparison. Two approaches were applied for the determination of log Pow values: calibration curve and phase ratio. In calibration curve approach, the MEKC retention factors (log k) of six alkyl phenyl ketones were plotted against their literature log Pow values for constructing the calibration curve. Log Pow values of benzene derivatives were then determined from the slope and the y-intercept of the linear calibration line. In the phase ratio approach, total surfactant concentration, critical micelle concentration, partial specific molar volume and experimental log k values were utilized for estimation of the log Pow values. Both approaches provided comparable results for HBA solutes; however, the calibration curve approach and phase ratio approach were found to be more successful for NHB and HBD solutes, respectively. In general, gemini surfactants provided better estimated log Pow values for NHB and HBA solutes while SDS gave better values for HBD solutes.