Ion-Pair Agents and Cogent TYPE-C™ Silica Columns

In most cases, ion-pair agents are not required when using Cogent TYPE-C Silica™ columns. These reagents are typically employed in reversed-phase (RP) methods to either:

• Increase retention of poorly retained compounds, or
• ​ Improve peak shape by reducing silanolic tailing.

Why TYPE-C™ Columns Minimize This Need:

• The silica hydride surface has very few silanol groups, significantly reducing tailing.
• ​ These columns support Aqueous Normal Phase (ANP), which provides strong retention for polar compounds without ion-pair agents.

Performance Advantages:
ANP has been shown to effectively analyze:

• Charged compounds (positive or negative) with molecular weights <100
• Larger molecules such as peptides
• ​ Most polar uncharged compounds

Mobile Phase Guidelines:

• Use additives at ≤10 mM (e.g., formic acid, acetic acid, ammonium acetate, or ammonium formate). These are MS-compatible and do not cause ion suppression.