Investigation of the properties of hypercrosslinked polystyrene as a stationary phase for high-performance liquid chromatography

The mechanical rigidity, swelling properties, adsorption selectivity, and chromatographic performance of hypercrosslinked polystyrene (mainly MN-200 or Purosep-200; Purolite, UK) have been studied to evaluate the use of the material as a stationary phase for reversed-phase high-performance liquid chromatography (RPHPLC). By use of inverse size-exclusion chromatography (SEC) this adsorbent, with a high specific surface area of 1500 m2 g−1 was found to have a biporous structure with micropores of ca 1–2 nm and macropores ca 100 nm in diameter. The polymer does not change its volume significantly on changing water for organic solvents. The retention increments for methylene and phenyl groups were calculated and indicated that the mechanism of retention on the hypercrosslinked polystyrene involves π-π interactions and strong hydrophobic interactions. The column performance of the hypercrosslinked polystyrene was found to be acceptable, with reduced plate height increasing very slowly as the linear velocity of the mobile phase increased to high values (up to 20–45 cm min−1). Columns containing hypercrosslinked polystyrene were evaluated for the separation of phenols, dialkyl phthalates, and polyaromatic compounds. On-column preconcentration of trace organic compounds from aqueous media is possible. With smaller particles of hypercrosslinked polystyrene becoming available, this material can be regarded as an alternative to alkylsilica as a hydrolytically stable column-packing material for RPHPLC.