The Cogent UDA™ HPLC Column is a TYPE-C™ silica hydride stationary phase designed primarily for HILIC and weak cation-exchange (WCX) chromatography. The bonded undecanoic acid functionality provides both hydrophilic interaction and weak cation-exchange characteristics, making this column especially useful for positively charged analytes, amine-containing compounds, nucleotides, and other highly polar molecules.

This guide provides recommended startup procedures, method development strategies, storage instructions, and best practices to help maximize column performance and lifetime.

Related Resources

• View Cogent UDA HPLC Column Ordering Information
• View General Instructions for All Cogent TYPE-C HPLC Columns

Choosing the Appropriate Separation Mode

HILIC / Weak Cation Exchange (Recommended)

Cogent UDA is specifically designed for polar compounds and positively charged analytes.

Typical Applications

• Aminoglycoside antibiotics
• Nucleotides
• Quaternary ammonium compounds
• Polar pharmaceuticals
• Amines
• Cationic compounds
• Metabolites

Example Compounds (Structures shown below)

• Cetylpyridinium Chloride
• Adenosine Triphosphate (ATP)
• Tobramycin

Increasing Retention

To increase retention:

• Increase organic solvent content.
• Reduce aqueous content.
• Optimize buffer concentration and pH.

Reversed-Phase (Limited Use)

Because UDA contains only limited hydrophobic functionality, reversed-phase applications are generally restricted.

For typical non-polar compounds consider:

• Cogent Bidentate C18™
• Cogent Bidentate C8™
• Cogent Phenyl Hydride™
• Cogent UDC-Cholesterol™

Important Precautions Before Use

Avoid Phosphoric Acid

Phosphoric acid should not be used with Cogent UDA columns.

Use of phosphoric acid may permanently alter the stationary phase and negatively impact column performance and longevity.

General System Preparation

Before installation:

1. Purge all solvent lines of previous mobile phases.
2. Purge the injector system.
3. Use fresh HPLC-grade solvents.
4. Degas mobile phases prior to use.
5. Prepare fresh buffers daily.

Startup Instructions

Initial Conditioning

1. Install the column using standard laboratory procedures.
2. Verify all fittings and tubing are properly connected.
3. Condition the column using a 50:50 organic solvent/water mixture containing all intended mobile-phase additives.
4. Equilibrate for approximately 30 minutes.
5. Transition to the starting mobile-phase conditions for the method.

Column Protection

For difficult sample matrices or aggressive conditions:

• Use guard columns whenever possible.
• Use inline filters whenever possible.
• Replace protection devices routinely.

Related Resource

• View TYPE-C Column Specifications and Troubleshooting Guidelines

HILIC and WCX - Weak Cation Exchange Method Development

General Method Development Strategy

The carboxylic acid functionality on the UDA phase enhances interactions with:

• Positively charged analytes
• Amines
• Nitrogen-containing compounds
• Certain highly polar molecules

To Increase Retention

• Increase acetonitrile content.
• Decrease aqueous content.
• Optimize ionic strength and pH.

Polar Neutral Compounds

Only sufficiently polar neutral compounds are likely to exhibit useful retention.  The same general strategy used for acidic compounds can often be applied successfully.

Acidic Compounds

To maximize retention:

• Ensure analytes remain ionized when appropriate.

Recommended starting buffer:

• 10 mM ammonium formate
• or
• 10 mM ammonium acetate

Recommended starting pH:

• Approximately 6.5

Simple Samples

Begin with:

• 50% aqueous buffer
• 50% acetonitrile

Increase organic content until adequate retention is achieved.

Complex Samples

Suggested scouting gradient:

• 90% acetonitrile
• To 20% acetonitrile
• Over approximately 10 minutes

Optimize as needed for resolution and selectivity.

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