I am confused when it comes time to use Phenyl, Amino or Cyano Columns. What are the main differences?
All these columns will offer different selectivities in reverse phase compared to a C18 or C8 column. Amino, and Cyano columns can be used as both normal and reverse phase; it is best to dedicate a particular column for either reverse or normal phase and not to change back and forth. Phenyl columns are more robust and rugged than cyano and amino but normally used only in reverse phase separations. Phenyl columns like C18 or C8 tend to retain samples based on hydrophobicity. A mixed interaction involving hydrogen bonding and dipolar interactions are responsible for the retention of solutes on cyano-silica columns and weak hydrogen bonding interaction leads to separation on amino-silica columns. Note: Cogent Type C columns can be used in both Reversed and Normal Phase modes. A simple 30 minute procedure allows switching from one mode to another. Procedure: A for moving from RP-HPLC to NP-HPLC pump 100% methanol for 15 minutes at 1 mL/min. flow rate, followed by 15 minutes 100% methylene
