CGP-50068

The higher diffusivity and lower viscosity of supercritical and near-critical fluids can make packed-column supercritical fluid chromatog. or subcritical fluid chromatog. (SubFC) faster with improved resolution over normal-phase HPLC for chiral separationsHowever, superior fluid characteristics do not guarantee enhanced resolution or shorter anal. time.In the case of phenylalaninol, a ¹H NMR spectrum indicates interaction of the solute with carbon dioxide.Such interaction may explain the poorer resolution achieved by SubFC than by HPLC.For a secondary amine, its ¹H NMR spectra showed no shift while poorer resolution was again observed for SubFC when compared to HPLC.Thus, the NMR data by itself do not conclusively indicate either reaction between basic solutes and carbon dioxide or the likelihood of chiral resolutionThe effects of column outlet pressure, organic modifier composition, pump flow-rate and column temperature for hydroxyzine were studied.Of the phys. parameters studied, modifier composition has the greatest impact on retention.Increasing retention generally increases resolutionChanging temperature generally has less impact on retention but produces the greatest selectivity changes.