CHEMICALLY BONDED PHENYLSILICONE STATIONARY PHASES FOR THE LIQUID-CHROMATOGRAPHIC SEPARATION OF POLYCYCLIC AROMATIC-HYDROCARBONS AND CYCLOSILOXANES

Chemically bonded phenylsilicone stationary phases, prepared from poly methylphenylsiloxane (PMPS) bonded silica gel, have been developed for use in high-performance liquid chromatography (HPLC) to separate comp ounds containing aryl groups through pi-pi interaction. Silanol-termin ated PMPS was synthesized through living anionic polymerization of met hylphenylcyclotrisiloxane. The PMPS bonded phases, with different degr ees of polymerization (DP), were prepared by bonding silanol-terminate d PMPS directly onto silica gel. The stationary phases thus prepared w ere characterized by elemental analysis, gel permeation chromatography , IR, H-1 NMR and Si-29 NMR. Evaluation of their chromatographic behav ior in relation to small PAHs (polycyclic aromatic hydrocarbons) and v arious cyclosiloxanes showed them to have reasonable separation abilit y in both normal-phase and reversed-phase. Copolymerization reactions of trifluoropropylmethylcyclotrisilioxane (F-3) and hexaphenylcyclotri siloxane (P-3) were followed on these stationary phases, and their per formance in the retention of phenyl-containing siloxane copolymers wit h different compositions was also evaluated. Comparison of these PMPS phases with a commercial ODS (C-18) phase in analyses of PAHs and cycl osiloxanes indicates clearly the significant contribution made by the phenyl moiety on the siloxane backbone to the pi-pi interaction in the HPLC separation process.