Liquid exclusion-adsorption chromatography: new technique for isocratic separation of nonionic surfactants. I. Retention behaviour of fatty alcohol ethoxylates
a Institute of Chemistry, Karl-Franzens-University, A-8010 Graz, Austria
b Institute for Highly Pure Biopreparations, Pudozhskaya 7, 197110 St. Petersburg, Russia
Abstract:
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.