Cogent UDC-Cholesterol™ or Cogent Bidentate C18™ HPLC Columns, which are based on the evolutionary TYPE-C Silica™ you can use these columns in:

Aqueous reverse phase = RP
Aqueous normal phase  = ANP
Organic normal phase   = ONP

To avoid confusion it is best to define ANP and ONP as separate techniques, but they are in reality different ends of the same mode; hexane/ethyl acetate as a mobile phase or 60+% Acetonitrile/water (for ionic compounds at appropriate pH) are both normal phase systems that work well on Cogent TYPE-C™ columns. Normal Phase: Retention times decrease as most polar solvent % increases Reverse Phase: Retention times increase as most polar solvent % increases

Storage Solvents for Reverse Phase or Aqueous Normal Phase:
If RP and ANP are your desired next usage for these columns, storage in a mixture of 40% Distilled Water that is acidified with 0.1% v/v formic acid and 60% Acetonitrile is recommended. If required, 100% Acetonitrile may be used.
Click here to view storage procedure

Storage Solvents for Organic Normal Phase:
If ONP is your desired next usage for these columns, storage in hexane is recommended.
Click here to view storage procedure

Note:
Due to the immiscibility of many organic normal phase (ONP) solvents and aqueous NP/RP based solvents, conversion from ONP to ANP/ARP can be best effected by flowing a mutually miscible solvent, such as methylene chloride, through the column for 15 bed volumes, prior to re-equilibration in the aqueous or organic based solvents to be next used. A simple 30 minute procedure (see below) 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 chloride. Column is ready to be equilibrated with mobile phase for NP-HPLC.

B – for moving from NP-HPLC to RP-HPLC pump 100% methylene chloride for 15 minutes at 1 mL/min. flow rate, followed by 15 minutes 100% methanol. Column is ready to be equilibrated with mobile phase for RP-HPLC.

Due to the minimal water bonding to the TYPE-C Silica™ particle surface, bonded and un-bonded TYPE-C™ columns equilibrate from organic/aqueous and to pH changes much quicker than most irregular, type-A or type-B based columns.

Important:
Store column at room temperature.
Never let the column dry out.
Never store the column intended for use in RP HPLC in solvents containing DI water without the suggested 0.1% formic acid.

Storage Procedures

How to Store: Cogent Bidentate C8™, Cogent Bidentate C18™ Cogent UDC-Cholesterol™ HPLC Columns

Overnight:

1. Rinse the column with 8-10 column volumes with a mixture of 40% distilled water that is acidified with 0.1% v/v formic acid and 60% acetonitrile. If required 100% acetonitrile can be used instead. Cap the ends of the column with the protective end caps or column plugs provided. Leaving ends of the column open will cause permanent damage to the column.

1. Rinse the column with 15 – 20 column volumes of 40% distilled water that is acidified with 0.1% v/v formic acid and 60% acetonitrile. If required 100% acetonitrile can be used instead. Cap the ends of the column with the protective end caps or column plugs provided.
2. Return column to the box it came in for safekeeping.
3. Store column at room temperature.

1. Rinse the column with 8-10 column volumes of 100% Hexane or other non polar solvent.
2. Cap the ends of the column with the protective end caps or column plugs provided. Leaving ends of the column open will cause permanent damage to the column.

1. Rinse the column with 15 – 20 column volumes of 100% hexane or other non polar solvent.
2. Cap the ends of the column with the protective end caps or column plugs provided.
3. Return column to the box it came in for safekeeping.
4. Store column at room temperature.
5. MARK THE COLUMN AS DESIGNATED FOR ORGANIC NORMAL PHASE AND WRITE WHAT SOLVENT IS INSIDE.