SOLUTION PROPERTIES OF POLYELECTROLYTES .12. SEMI-QUANTITATIVE APPROACH TO MIXED ELECTROSTATIC AND HYDROPHOBIC POLYMER-GEL INTERACTIONS

摘要

Aqueous size-exclusion chromatography of polyanions, where secondary effects affect the total separation mechanism, was investigated. For elution of polyelectrolytes on inorganic silica-based supports, the electrostatic polymer-gel repulsive interactions were evaluated through the values for a hypothetical repulsion layer, X(c), according to the model developed by other workers. Using a similar procedure, the existence of an effective barrier defined as X(c) - X(h) is proposed for those systems in which electrostatic repulsion and hydrophobic interactions take place simultaneously as secondary mechanisms. X, can be viewed as a measure of the ''enlargement'' of the geometrical pore radius due to reversible adsorption of polyanions in organic polymeric packings. In the light of the values of this effective barrier on the pore surface, the intensity and contribution of each type of solute-matrix interaction to the overall chromatographic process can be analysed as a function of polymer size and mobile phase composition, pH and ionic strength.