Retention in reversed-phase liquid chromatography: solvatochromic investigation of homologous alcohol-water binary mobile phases.
The mechanism of retention in reversed-phase liquid chromatography (RPLC) has been further investigated using the ET(30) solvatochromic solvent polarity scale. The retention behavior of a variety of solutes was measured using a homologous series of normal alcohols as the organic modifiers in hydroorganic mobile phases. The results imply that a systematic change in the extent of solvation of the stationary phase occurs with respect to the size of the organic modifier. It was also found that a linear extrapolation of the log k' versus ET(30) plots for different mobile phases using methanol, ethanol and acetonitrile (but not n-propanol) as modifiers, intersected at approximately the ET(30) value of pure water. This intersection is further evidence that the ET(30) model of solute retention is a useful tool with which to study the mechanism of retention in RPLC. The extrapolated retention value in water, log k'w, from the ET(30) plots should then prove to be a more reliable means of estimating solute lipophilicity using RPLC than the percent organic modifier model.
Michels
J J
JJ
Department of Chemistry, University of Florida, Gainesville 32611.
Dorsey
J G
JG
D000438:Alcohols / Q000032:analysis*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002853:Chromatography, Liquid / Q000379:methods*; D014867:Water
D000438:Alcohols; D014867:Water