Displacement chromatography on cyclodextrin-silicas. I. Separation of positional and geometrical isomers in the reversed-phase mode.
The retention behaviour of several charged and uncharged solutes on beta-cyclodextrin-silica was studied as a function of the methanol concentration, ionic strength and pH of the eluent in order to develop efficient displacement chromatographic separations for positional and geometric isomers. These retention curves were used to predict the eluent (carrier solvent) compositions that result in solute retentions in excess of k' = 10. The adsorption isotherms of several cationic detergents were determined in these carrier solutions and were found to be convex. The adsorption isotherms of several positional isomers used as test solutes were also determined in these carrier solutions. The adsorption isotherms permitted the development of efficient displacement chromatographic separations for the isomers tested. Column loadings as high as 58 mg were achieved on a regular 4.6 mm I.D. analytical-scale cyclodextrin silica columns.
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Chemistry Department, Texas A & M University, College Station 77843-3255.
Quintero
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Farkas
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D002853:Chromatography, Liquid / Q000379:methods*; D003505:Cyclodextrins; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D009994:Osmolar Concentration; D012031:Refractometry; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
D003505:Cyclodextrins