SWELLING BEHAVIOR AND KINETIC PERFORMANCE OF POLYACRYLATE STATIONARY PHASES FOR REVERSED-PHASE AND NORMAL-PHASE OPEN-TUBULAR LIQUID-CHROMATOGRAPHY

The effect of the mobile phase composition on the kinetic performance and retention behaviour of polyacrylate films, used as stationary phas es in open-tubular liquid chromatography (OT-LC), was investigated. Th e polyacrylate films studied consisted of the copolymers silicone acry late-ethylhexylacrylate (SIA-EHA), silicone acrylate-ethoxyethylacryla te (SIA-EEA) and silicone acrylate-hydroxyethylacrylate (SiA-HEA). All polyacrylate films swell significantly in pure organic solvents like methanol and hexane compared to aqueous-organic solvent mixtures. Unde r the latter conditions the kinetic performance decreased dramatically except for the SiA-HEA stationary phase. The swelling and shrinking o f the stationary phase is fast; within one column volume the equilibri um is attained when changing the mobile phase composition. The moderat e polarity of the polyacrylate stationary phase allows chromatographic use of the capillaries in the reversed-phase as in the normal-phase m ode.