Flow field-flow fractionation of poly(ethylene oxide): effect of carrier ionic strength and composition

The effects of carrier ionic strength and electrolyte composition on the retention of poly(ethylene oxide) in aqueous flow field-flow fractionation have been investigated in this work. The study shows retention to be particularly sensitive to the presence of salts, as well as to the nature of the cation. Specifically, retention effects due to sample load are found to be very different in solutions containing potassium salts compared to those observed in solutions of the corresponding sodium salts. In a potassium-containing medium, the dependence of retention on sample mass is similar to that found previously for polyelectrolytes. This effect, which is particularly prominent for samples of low molecular mass, can be attributed to specific interactions between cation and polymer.