Direct Si–C Bonds on Cogent TYPE‑C™ Columns: Why They Deliver Longer Column Life and Cleaner Chromatography
Why bonded‑phase stability matters
Most conventional silica columns (C8, C18, NH₂, etc.) attach ligands to the silica surface through a siloxane bridge (–Si–O–Si–C–). Under certain mobile‑phase conditions, that Si–O linkage is the weak point: it can hydrolyze, cleaving the bonded phase from the particle, which shortens lifetime and can shed material into the LC system.
The TYPE‑C™ advantage: true Si–C bonding
Cogent TYPE‑C™ columns employ a direct silicon–carbon (Si–C) bond to anchor the ligand to a silica‑hydride surface. Because the oxygen atom is absent from this attachment, the linkage is far more resistant to hydrolysis. In practice, this greatly reduces phase loss/bleed, extends column lifetime, and preserves selectivity over longer sequences and harsher conditions.
What you gain in day‑to‑day work
- Longer service life and ruggedness: Si–C bonded phases endure challenging mobile phases and temperatures that can degrade siloxane‑bonded columns, improving reproducibility over time.
- Cleaner systems: With no measurable phase bleed from hydrolytic cleavage, instruments stay cleaner and MS sources require less maintenance.
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Method freedom: The stability of the Si–C anchor lets you explore mobile‑phase additives and elevated temperatures that might be impractical with standard columns—useful for difficult separations and robustness testing.
Expanded chemistry options on silica‑hydride
Traditional Type‑B silica platforms (relying on organosilane routes to form siloxane linkages) limit the palette of ligands you can attach. The patented silica‑hydride surface used in TYPE‑C™ overcomes those limits, enabling bonding of chemistries previously considered incompatible with silica—including unique phases like UDC‑Cholesterol™—and supporting custom phase development when needed.
Quick Reference: Conventional vs. TYPE‑C™ Attachment
|
Platform |
Attachment to Silica |
Hydrolysis Susceptibility |
Practical Effect |
|---|---|---|---|
|
Conventional Type A/B silica |
Siloxane bridge Si–O–Si–C |
Higher (Si–O can cleave in water/acid/base ranges) |
Shorter life; potential phase bleed; selectivity drift over time |
|
Cogent TYPE‑C™ silica‑hydride |
Direct Si–C bond |
Much lower |
Longer lifetime, cleaner system, stable selectivity, broader method space |
Practical tips for method developers
- If you’re seeing gradual retention/selectivity drift or column failures after aggressive rinses or extended sequences, consider switching to TYPE‑C™ Si–C bonded phases to mitigate hydrolytic loss.
- For stubborn separations, leverage Si–C robustness to pilot higher temperatures or alternative additives—often unlocking selectivity not feasible on siloxane‑bonded columns.
- When you need non‑standard ligands (e.g., UDC‑Cholesterol™) or specialty selectivity, the silica‑hydride platform supports attachment of chemistries not easily bonded on conventional silica.
