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Introduction
Phenyl-bonded silica columns offer an alternative reversed-phase selectivity. They show similar retention characteristics to C8-bonded phases but exhibit a different selectivity for aromatic compounds. Nitrophenyl- and pentafluorophenyl¬bonded phases offer further selectivity alternatives, especially for fluorine-containing molecules.
Traditional phenyl phases tend to be less stable than the corresponding C8 or C18 reversed-phases. The larger steric size of the phenyl group reduces surface coverage leaving a greater number of exposed silanol sites. More recently introduced phenyl phases show greater stability. The use of a purer silica base, more effective and reproducible bonding procedures and the availability of a sterically protected phenylsilane all contribute to greater phase robustness.
Phenyl-Bonded Phases
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