PFP is a truly unique stationary phase with properties significantly different from ODS phases. This unique character results from bonded pentafluorophenyl groups imparting a pi-pi electron interaction, producing an enhanced retention from many compounds, particularly those that contain polarizable electrons. Many classes of compounds and naturally occurring chemicals also contain polarizable electrons and can be separated using PFP. PFP has bee extremely useful in the separation of epimers. Epimers also exist in many natural mixtures such as pharmaceutically active natural paclitaxel.