Solvent Strength Parameters and Retention Factors in Pure Water Using UNIFAC-Predicted Activity Coefficients

Jung Hag Park, Yun Jung Jung, Mark F. Vitha, Peter W. Carr

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

It is well-known in reversed-phase liquid chromatography that the solute retention factor (k) in binary eluents is well modeled as a quasi-linear function of the eluent composition (Φ) by the equation log k = log k s/w - SΦ, where the solute parameters ks/w and S are the retention factor in pure water and the solvent strength parameter, respectively, and Φ is the volume fraction of the organic component of the eluent. S is related to the free energy of the solute transfer from water to bulk organic liquid, which in turn is related to the infinite-dilution activity coefficients (γ) of the solute in water and bulk organic liquid. We report that the γ values obtained from a γ prediction model, UNIFAC, can be used to predict S directly and also to aid in the determination of best-fit k s/w values for acetonitrile-water mobile-phase systems. More specifically, UNIFAC-based S values combined with experimentally determined ks/w values for a limited set of solutes can be used to predict the variations in retention as a function of mobile-phase composition in acetonitrile-water systems within the calibration range for solutes that were not in the original data set.

Original languageEnglish (US)
Pages (from-to)6320-6330
Number of pages11
JournalIndustrial and Engineering Chemistry Research
Volume42
Issue number25
DOIs
StatePublished - Dec 10 2003

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