Analysis of ethoxylated nonylphenols by combination of HPLC and CZE

Abstract

The separation of samples of ethoxylated nonylphenol type surfactants by twodimensional method combining liquid chromatography with capillary zone electrophoresis has been studied. In the first part of the work, separation conditions using reversed-phase liquid chromatography with isocratic elution were optimized. Thus six different stationary phases were compared to provide highest resolution of ethoxylated nonylphenol surfactants with various degrees of ethoxylation in water/methanol and water/acetonitrile mobile phases. The separation of nonylphenol branch isomers was carried out using capillary zone electrophoresis in non-coated and poly(acryl amide) coated capillaries employing solvofobic interaction approach in background electrolyte containing sodium dodecyl sulfate and acetonitrile. Finally, nonionic surfactants were analyzed using combination of optimized methods of liquid chromatography and capillary zone electrophoresis in off-line automated two-dimensional system.