Solution Properties of Poly-Electrolytes. XI. Adsorption Effects in Aqueous Size-Exclusion Chromatog-Raphy of Polyanions

摘要

Elution profiles of a series of polymer standards such as sodium poly(styrene sulphonate), poly(acrylic acid) and poly(L-glutamic acid) have been obtained from size-exclusion chromatography experiments using separately two types of hydrophilic supports. A variety of mobile phase compositions have been performed to enhance adsorption effects in order to study how this phenomenon can affect to the chromatographic separation mechanism of polyanions. Distribution coefficient values, in general greater than unity, have served to quantify the adsorption effect, as well as to analyze their dependence on eluent ionic strength, on the ionic groups of the support and on the chemical nature and molar mass of the polyion. The physical basis of the weak polymer-gel attractive interaction have been attributed to hydrogen-bonding and to hydrophobic effects. We present basic equations derived from the Flory-Huggins theory of polymer solutions to explain the adsorption process in terms of preferential interaction, being this description consistent with the expected values assigned to the interaction parameters involved in the above theory.