Aqueous gel permeation chromatography of polyelectrolytes and salt exclusion effect

The dependence of the elution volume of NaCl samples is discussed as a function of the volume and concentration injected and of the ionic strength of the eluent. The same is done with two fractions of polystyrene sulphonic acid in the sodium form. It is concluded that the exclusion depends directly on the screening parameter proportional to $\text{μ}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$ for NaCl and that a steric parameter has to be added with polyelectrolytes, depending on the molecular weight and on the ionic strength of the eluent. The behaviour is directly correlated to the pore size distribution in the gel.