Reversed-phase chromatography, which permits organic solvents of certain composition as mobile phase to suit experimental conditions, is used at large for many successful applications. Yet selectivity and robust separations are evasive in many separations intended. In fact differences in selectivity are most often encountered when analyzing mixtures of relatively polar compounds. Many polar compounds prefer a highly aqueous mobile phase up to 100% or with a minimal proportion of organic solvent.
Chromasol ONYX AQ column has reversed-phase media with both hydrophobic and a relatively hydrophilic surface. Because of the hydrophilic surface, the media can be “wetted” with more polar mobile phases. This column offers superior retention of polar compounds and excellent reproducibility in highly aqueous mobile phases even in 100% aqueous mobile phase. This column provides reproducible retention and excellent peak shape in highly aqueous mobile phase. A comparison of the performance of Chromasol ONYX AQ and Chromasol ONYX C18 columns under identical chromatographic test conditions for test mixtures with polar and non-polar reagents in high aqueous mobile phases is illustrated in the Figures.