Preparing and Storing Cogent TYPE-C Silica™ HPLC Columns

This guide explains best practices for initial preparation and proper storage of Cogent TYPE-C Silica™ columns to maintain performance and prevent degradation—whether for overnight or long-term storage.

Storage Solvents by Mode

• Reversed Phase (RP) or Aqueous Normal Phase (ANP):
  Store in 100% Acetonitrile if these modes will be used next.

• Organic Normal Phase (NP):
  Store in 100% Hexane for NP applications.

Important Note on Mode Switching

Because many organic NP solvents are immiscible with aqueous RP/ANP solvents, switching modes requires an intermediate solvent. Use methylene chloride (mutually miscible) for 15 column volumes before re-equilibrating in the next mobile phase. This simple 30-minute procedure prevents phase incompatibility issues.

Mode Conversion Procedures

• RP → NP:

  1. Pump 100% Methanol for 15 min at 1 mL/min.
  2. Pump 100% Methylene Chloride for 15 min.
     Column is ready for NP equilibration.

• NP → RP:

  1. Pump 100% Methylene Chloride for 15 min at 1 mL/min.
  2. Pump 100% Methanol for 15 min.
     Column is ready for RP equilibration.

Why TYPE-C Silica™ is Different:
Minimal water adsorption allows fast equilibration between organic/aqueous phases and pH changes—much quicker than Type-A or Type-B silica columns.

Critical Storage Guidelines

• Store at room temperature—never refrigerate or heat.
• Never let the column dry out.
• For RP use, do not store in DI water without 0.1% formic acid.

Storage Procedures

For RP or ANP Use

• Overnight:
  1. Flush with 8–10 column volumes of 100% Acetonitrile.
  2. Cap both ends securely with provided plugs.
• Long-Term:
  1. Flush with 15–20 column volumes of 100% Acetonitrile.
  2. Cap ends and return to original box.
  3. Store at room temperature.

** Diamond Hydride™ columns have a special storage protocol, given click HERE.

For Organic NP Use

• Overnight:
  1. Flush with 8–10 column volumes of 100% Hexane (or other non-polar solvent).
  2. Cap ends securely.
• Long-Term:
  1. Flush with 15–20 column volumes of 100% Hexane.
  2. Cap ends, return to box, and store at room temperature.
  3. Label the column for NP use and note the solvent inside