INFLUENCE OF INJECTED MASS AND IONIC-STRENGTH ON RETENTION OF WATER-SOLUBLE POLYMERS AND PROTEINS IN HOLLOW-FIBER FLOW FIELD-FLOW FRACTIONATION

The retention behaviour of water-soluble polymers and proteins in holl ow-fibre flow field-flow fractionation was studied. For a charged poly mer such as polystyrene sulphonate (PSS), a low ionic strength of the carrier solution can completely disturb the retention mechanism by ove rloading, resulting in early-eluting, deformed peaks. Overloading was observed at polymer concentrations far below the so-called semidilute region. Under conditions where overloading effects could be observed, no evidence was found for a threshold value of the amount injected bel ow which overloading did not occur. For proteins the influence of the ionic strength on overloading is less than for PSS, although there is an effect when the pH of the eluent is not at the isoelectric point of the protein. In contrast, non-charged pullulan is not effected by the ionic strength of the eluent and much larger amounts can be injected before significant overloading occurs.