Covalently bound ionene polyelectrolyte-silica gel stationary phases for HPLC

Micelle-mimetic ionene-based stationary phases for highperformance liquid c hromatography (HPLC) are prepared by attaching [3,16]- and [3,22]-ionenes t o aminopropyl silica through a carbon-nitrogen bond. These [x,y]-ionenes ar e polyelectrolytic molecules consisting of dimethylammonium charge centers interconnected by alternating alkyl chain segments containing x and y methy lene groups, some of which can form aggregate species whose properties mimi c those of conventional surfactant micelles, These ionene-bonded stationary phases were characterized using different recommended HPLC test mixtures. Test solute chromatographic behavior on the ionene phases was found to be s imilar to that of intermediate oligomeric or polymeric C-18 and/or phenyl p hases, depending upon the specific test mixture employed. In addition, the phases exhibit significant solute shape recognition ability. The ionene sta tionary phases were successfully employed for the separation of the compone nts of the recommended ASTM reversed-phase test mixture, as well as for ort ho-, meta- and para-disubstituted benzenes and other positional or geometri c isomeric compounds. The ionene materials allow for chromatographic separa tions under either reversed-phase or ion-exchange conditions. The retention mechanism on these multimodal phases can occur by hydrophobic partitioning or electrostatic interactions, depending upon the characteristics of the c omponents of the analyte mixture (neutral or anionic), The effects of alter ation of the percent organic modifier, flow rate and temperature of the mob ile phase on chromatographic retention and efficiency on these phases were briefly examined.