About Cogent TYPE-C™ Silica HPLC Columns

Method development with TYPE-C columns is straightforward, as the mobile phase for both polar and non-polar compounds remains the same, with only the gradients differing in their starting and ending points. Like all modern HPLC columns, these columns are optimized and perform best when a method specifically developed for the column and sample is used.

Each column undergoes individual testing to ensure specification conformance and is supplied with a test chromatogram. Choose from analytical, preparative, and guard column formats. Our laboratory is fully equipped to support method optimization and troubleshooting, and our technical team is eager to assist with any questions you may have. All Cogent HPLC columns can be manufactured with metal-free coated stainless steel hardware.

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Cogent TYPE-C™ Silica HPLC columns, introduced in 2001, represent an advancement over other, standard chromatographic supports and phases for polar compounds. The silica surface is populated with highly stable silicon-hydride groups (Si-H) and not silanol groups (Si-OH). Unlike other silica used in HPLC, which are known to be extremely hydrophilic, the surface of these particles is slightly hydrophobic. This unique characteristic makes TYPE-C™ Silica Columns valuable to chromatographers. In the presence of 2% or more water in the mobile phase, the surface becomes charged by the adsorption of H+ ions produced from the auto-dissociation of water. Very polar compounds are selectively and precisely retained when the mobile phase is largely organic, while less polar compounds are retained even at low concentrations of organic solvents (as low as 20% organic).

TYPE-C™ Silica particles retain all the physical advantages of standard silica, such as spherical shape, low metal content, high purity, high mechanical strength, narrow pore size distribution, a wide range of pore sizes, ease of chemical modification, and no swelling in the presence of solvents, ensuring stable packed beds.

Another major advantage of using Cogent TYPE-C™ HPLC Columns, compared to industry-leading standard columns, is that a single TYPE-C™ column can be used for three different modes of HPLC: Reversed Phase, Normal Phase, and Aqueous Normal Phase (ANP) / HILIC. Other columns on the market do not offer such selectivity power or versatility in a single stationary phase. But the most popular feature of these columns is for use with polar compounds especially with LCMS. Increased sensitivity, fast equilibration, high organic starting points in the gradients and low salt required for retention makes these columns the ideal choice for polar compounds over HILIC, Ion Exchange or mixed mode phases.

Due to the unique nature of these phases, a single column can sometimes separate both polar and non-polar compounds simultaneously or in different runs with different mobile phases. This capability accelerates method development, impurity scouting, and the identification of degradation products, among other applications.

Since one column can be used for Reversed Phase, Normal Phase (with non-polar solvents such as hexane), and Aqueous Normal Phase (ANP), these columns offer additional benefits over HILIC Columns, including but not limited to: precision, fast equilibration (including gradients), lower salt usage to retain polar compounds, smaller sample sizes, and differences in elution and resolution with bonded phases such as Bidentate C18, Phenyl, Diol, Amide, Bidentate C8, UDC-Cholesterol, UDA (WCX), and the popular Diamond Hydride.

Strong adsorption of water to ordinary silica is well known and well documented. However, the silicon-hydride groups (Si-H) found on the surface of Cogent TYPE-C Silica™ Phases are not prone to such strong water retention. This weaker water adsorption also accounts for the minimal to no hysteresis observed when transitioning between Organic-Normal, Aqueous-Normal, and Reversed Phase methods. It also applies when changing the sample pH and the pH of the mobile phase or when equilibrating between gradient runs. This allows for rapid equilibration between runs and improved precision.

The absence of this water layer suggests that Cogent TYPE-C columns have virtually no partitioning as a chromatographic mechanism. The primary mechanism of retention is ion interaction, which can be easily controlled by pH with great precision. The secondary mechanisms depend on the bonded ligands such as Cholesterol, C18, Phenyl, C3, DIOL, Amide and Undecanoic acd.