Retention of functional polymers in liquid adsorption chromatography: Effect of the end groups in PEGs and their methyl ethers in different mobile phases

It is shown that the end group parameter, which describes the influence of the end group on retention, can be determined in RP chromatography from two chromatograms of a nonfunctional and a monofunctional sample, if a sufficient number of peaks with the same number of repeat units in each sample can be reasonably resolved and identified. The same procedure can also be applied for pairs of di- and monofunctional polymers. End group parameters have been determined in three different mobile phases: acetonitrile water, acetone water and methanol water of different compositions. The temperature dependence of the interaction parameter of the repeat unit and the end group parameter has been found to be different, which allows a fine-tuning of retention.