Typical HPLC bonded phases (C8, C18, NH2 etc) are made with siloxane (Si-O-Si-C) bonds which are prone to hydrolysis. The oxygen in the this link is the weak point where the bonded phase is cleaved off the particle.

Silicon-Carbon bonds (available only on Cogent TYPE-C™ columns) are much more stable and resistant to hydrolysis and is therefore less phase bleed-off. This means that these columns will last much longer than ordinary columns and be more rugged and will be reproducible longer. This also means that you might be able to explore new mobile phase/additive and temperature conditions to achieve very difficult separations that might be impossible with your current HPLC columns.

Also, standard Type-B columns made with silanization of organo-silanes to produce siloxane bonded ligands limits the phases which may be bonded onto silica. With our patented, silica-hydride surface many compounds previous thought to be improbable to bond to silica can be easily bonded. Examples of this is our unique UDC-Cholesterol™, plus our unique ability to custom synthesis novel phases for our customers.