Comparison of Selectivity Differences Among Different Agilent ZORBAX Phenyl Columns using Acetonitrile or Methanol

Alkyl, most commonly C18, columns are used in reversed-phase HPLC method development. Occasionally additional bonded phases are tested in attempt to optimize the separation. Phenyl bonded phases are an excellent choice to consider when a C18 does not achieve separation. In this work, the unique selectivity of three Agilent ZORBAX phenyl phases is shown and compared against a ZORBAX C18. The phenyl columns are run in a methanol mobile phase, as well as acetonitrile. Scatter plots comparing the organic solvents, show increased slopes and stronger correlation with acetonitrile due to the suppression of π-π interactions that are present with methanol. While these π-π interactions are not solely responsible for retention on phenyl columns in methanol, they could provide a slight enhancement to complicated separations of closely related compounds. Authors William J. Long and Anne E. Mack Agilent Technologies, Inc. 2850 Centerville Road Wilmington, DE 19809 USA Application Note