SOLUTION PROPERTIES OF POLYELECTROLYTES .XI. ADSORPTION EFFECTS IN AQUEOUS SIZE-EXCLUSION CHROMATOGRAPHY OF POLYANIONS

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 se parately two types of hydrophilic supports. A variety of mobile phase compositions have been performed to enhance adsorption effects in orde r to study how this phenomenon can affect to the chromatographic separ ation mechanism of polyanions. Distribution coefficient values, in gen eral 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 m ass of the polyion. The physical basis of the weak polymer-gel attract ive interaction have been attributed to hydrogen-bonding and to hydrop hobic effects. We present basic equations derived from the Flory-Huggi ns theory of polymer solutions to explain the adsorption process in te rms of preferential interaction, being this description consistent wit h the expected values assigned to the interaction parameters involved in the above theory.