Liquid exclusion-adsorption chromatography: new technique for isocratic separation of nonionic surfactants I. Retention behaviour of fatty alcohol ethoxylates

A new technique of liquid chromatography is described, which allows a baseline separation of fatty alcohol ethoxylates with 15-20 ethylene oxide units under isocratic conditions. The new method is based on a combination of two different chromatographic modes for the individual structural units: size exclusion for the poly(oxyethylene) chain and adsorption interaction for the hydrophobic end fragments. A theory is provided for this mixed exclusion-adsorption mode of Liquid chromatography. Chromatographic data are found to be in a good agreement with this theory. (C) 2001 Elsevier Science B.V. All rights reserved.