A novel polar separation medium for the size exclusion chromatography of small molecules: Uniformly sized, porous poly(vinylphenol-co-divinylbenzene) beads

A novel separation medium based on uniform size beads of 4-hydroxystyrene-divinylbenzene call be used for both the size exclusion chromatography of small molecules and their separation by reversed-phase chromatography. The new 5 mu m material is prepared by the controlled swelling of monodispersed polystyrene particles, that serve both as porogen and shape template, with a polymerization mixture consisting of the monomers and dibutylphthalate,followed by a suspension polymerization. Removal of the acetoxy groups by hydrolysis with aqueous base leads to the final poly(4-vinylphenol-co-divinylbenzene) monodispersed beads. Polymerization conditions that favor the formation of very small pores were developed to optimize-the beads for the SEC separation of small molecules. The SEC calibration curve confirms that the optimized beads contain a large volume of pores suitable for the separation of solutes with a molecular weight of up to about 1000. The ability to separate alkylbenzenes according to their hydrodynamic sizes has been demonstrated using a column packed with this material. In addition, the phenol chemistry used in combination with a hydrophobic crosslinking monomer provides this separation medium with an unusual versatility that allows both reversed phase and normal phase chromatography to be run in the same column after a simple change of the mobile phase.