Stationary phase and bulk

The molecular architecture and the chain length of the IPR greatly affect analyte retention enhancement. At constant eluent composition, log k of an analyte oppositely charged to the IPR raises linearly with the number of carbon atoms in the chain of the alkyl sulfonate [2,3]. The shorter the IPR side chain, the lower its adsorption onto the stationary phase. This involves a lower potential difference between the electrified stationary phase and bulk eluent that in turn results in a lower driving force for analyte retention [4-7]. To attain comparable retention, the effect played by a higher concentration of a less hydrophobic IPR is tantamount to that of a lower concentration of a more lipophilic IPR [8-10]. However, the relationship between adsorbophilicity and chain length of the IPR is only part of the story. 

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