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

Aqueous size-exclusion chromatography of polyanions, where secondary e ffects affect the total separation mechanism, was investigated. For el ution of polyelectrolytes on inorganic silica-based supports, the elec trostatic polymer-gel repulsive interactions were evaluated through th e values for a hypothetical repulsion layer, X(c), according to the mo del developed by other workers. Using a similar procedure, the existen ce of an effective barrier defined as X(c) - X(h) is proposed for thos e systems in which electrostatic repulsion and hydrophobic interaction s 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 surf ace, the intensity and contribution of each type of solute-matrix inte raction to the overall chromatographic process can be analysed as a fu nction of polymer size and mobile phase composition, pH and ionic stre ngth.