Influence of ionic strength, sample size, and flow conditions on the retention behavior of pullulan in flow field-flow fractionation

Polymer molecular parameters such as hydrodynamic size are expected to be invariant regardless of the technique used to measure them, and to vary only, to some extent, with the solvent power and the polymer structure and properties as predicted from polymer chemistry. The hydrodynamic size of five pullulan standards derived from FlFFF in solutions of different ionic strength appears to correlate well to molecular mass as expected for neutral polymers for all fractions except that of lower mass. The correlation also holds for large amounts of injected sample even though with a slope which increases with rising polymer load. The evidence that the same result is obtained also for low sample amounts but with a higher cross-flow rate is interpreted as the manifestation of the presence of hydrodynamic interactions in concentrated polymer systems.