Overview

A common question regarding Cogent™ Silica-C™ columns is whether the stationary phase contains carbon. Because many HPLC columns derive their chromatographic properties from carbon-containing ligands such as C18, C8, Phenyl, or Cholesterol phases, it is reasonable to assume that a column named "Silica-C™" may also contain carbon.

The answer is:  No. Cogent™ Silica-C™ stationary phases do not contain carbon as part of the stationary phase surface chemistry.

Stationary Phase Composition

The Cogent™ Silica-C™ stationary phase is based on TYPE-C™ silica hydride technology and is composed primarily of:

• Silicon
• Hydrogen
• Oxygen

Unlike traditional bonded-phase columns, Silica-C™ does not rely on a carbon-based surface ligand to provide chromatographic retention.

How Silica-C™ Differs from Traditional HPLC Columns

Many conventional HPLC columns use carbon-containing ligands bonded to silica particles, including:

• C18
• C8
• Phenyl
• Cyano
• Cholesterol

These ligands contribute significantly to retention through hydrophobic interactions.

Cogent™ Silica-C™, however, utilizes the underlying silica hydride surface without the addition of a carbon-based bonded chemistry.

This results in chromatographic behavior that can differ substantially from traditional reversed-phase stationary phases.

Retention Characteristics

Silica-C™ is commonly used for:

• HILIC methods
• Polar compound separations
• Normal Phase chromatography
• LC-MS applications
• Method development for challenging analytes

Under HILIC conditions, polar compounds often exhibit strong retention, especially when using:

• High acetonitrile mobile phases
• Low aqueous content
• Volatile mobile phase additives

Why Non-Polar Compounds May Still Show Retention

Some users observe retention of compounds that are not highly polar and assume this indicates the presence of carbon-based chemistry.

However, any observed retention is a consequence of:

• Mobile phase composition
• Analyte properties
• Interactions with the silica hydride surface
• HILIC or other retention mechanisms

It is not evidence of carbon-based bonded chemistry on the stationary phase.

Key Takeaways

• Cogent™ Silica-C™ does not contain carbon as part of the stationary phase surface.
• The stationary phase is composed primarily of silicon, hydrogen, and oxygen.
• Silica-C™ is part of the TYPE-C™ silica hydride column family.
• The column can be used for HILIC, Normal Phase, and other polar compound applications.
• Any retention observed is related to analyte and mobile phase interactions rather than carbon-based bonded chemistry.