Are Cogent TYPE-C Silica™ columns made with hybrid particles?

No, it is an evolution of standard, high purity, based deactivated, type-B silica with a very stable and unique surface that does not retain water as all other HPLC columns do. If you are using a commercially available silica based HPLC column, TYPE-C™ columns may be considered the same as what you are currently using […]

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Can ANP HPLC be used to retain steroids?

It always depends on the individual compounds but generally speaking ANP is best suited to compounds of a more polar nature.  In contrast, steroids as a class of compounds are mostly too hydrophobic for ANP and hence are generally poorly retained under these conditions. Reversed phase may be a more suitable chromatographic approach for retention and […]

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Can I use primary amines with acetone as the mobile phase component in LCMS?

Yes, you can. However, some labs react acetone with primary amines (+heat) to form acetone adducts (imines) in GC and GCMS. This reaction while using acetone as a mobile phase component in LCMS along with primary amines as part of the sample is something to consider. This reaction, according the University of Liverpool requires a primary amine, a ketone or aldehyde (in this […]

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Can you inject highly acidic samples on to Cogent TYPE-C Silica HPLC columns?

The Cogent TYPE-C™ Silica columns have certain specification ranges for pH that must be followed to avoid damage to the material. These specifications apply to the mobile phase eluent present in the column.  The amount of sample injected is so small compared to the mobile phase eluent that the effect is not significant. Therefore you should be able to inject […]

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Do Tanaka Plots apply to Cogent TYPE-C™ Silica HPLC Columns?

To answer this question, first we must define what Tanaka plots are. Nobuo Tanaka devised a set of chromatographic tests that are intended to characterize the properties of a given stationary  phase. The analyst performs a separation of various test solutes in the manner described by the Tanaka test and records the resulting chromatographic values obtained […]

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How do I condition new Cogent TYPE-C™ Columns for use?

For all new Cogent TYPE-C™ HPLC columns with the exception of new Diamond Hydride™ columns, all one needs to do is run 7-10 column bed volumes of your mobile phase through the column at your normal flow rate. Then it is best to inject a known standard and repeat the injections until duplicate chromatograms are […]

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How does efficiency in ANP compare to HILIC?

Aqueous Normal Phase (ANP) is a distinctly different retention mode than Hydrophilic Interaction Liquid Chromatography (HILIC). In HILIC, evidence has shown that retention is achieved by partitioning in and out of a water layer surrounding the stationary phase surface. With a much less polar surface, TYPE-C Silica columns do not exhibit this same partitioning retention behavior. Speculated local […]

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How often do I need to clean the Cogent TYPE-C Silica columns?

It depends on the type of samples you are working with. The purpose of cleaning the column is to remove contaminants that build up on the column from your samples. As such, injecting clean samples such as standards mean that the column will rarely need cleaning. On the other hand, biological or physiological samples have […]

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How to Store & Condition Cogent TYPE-C Silica™ HPLC Columns.

This article describes how best to prepare Cogent TYPE-C Silica™ HPLC Columns for Initial Use when you first receive them as well as How To Store them, for either Overnight or Long-Term Storage, to prevent Column degradation. Storage Solvents for Reverse Phase (RP) or Aqueous Normal Phase (ANP): If RP and ANP are your desired next use […]

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I am using a Cogent TYPE-C™column with LC-MS and solvents containing 10 mM ammonium acetate. I noticed that my source was getting white film on it. At the same time the background noise was very low. Is my column bleeding the packing material?

Cogent TYPE-C™ columns including the Cogent Diamond Hydride have a very low background noise even when used with LC-MS and the white film most likely comes from ammonium acetate build up from your mobile phase. These columns have been proven to be extremely durable and because of the direct silicon-carbon bonds of these phases, bonded phase bleed is almost […]

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I heard that there is Not a Good Alternative to HILIC to Achieve Sufficient Retention for some compounds. Is this true? – FAQ

This is an untrue statement that can lead chromatographers to frustration as THERE IS an alternative mode of chromatography that surpasses HILIC in reproducibility, precision and the ability to separate both hydrophobic and hydrophilic compounds. It is well documented that Aqueous Normal Phase HPLC (ANP) is a very viable alternative to HILIC for polar compounds and in many cases superior […]

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Many other column suppliers suggest different columns for Acids, Neutrals or Bases, which TYPE-C™ column is best for each of these compound groups?

The Cogent TYPE-C™ HPLC phases are unique in that they have different retention mechanisms which can be exploited to give unique separations. It may not be necessary to use different columns for different classes of compounds. Click here for real life examples of the Cogent TYPE-C™  and other HPLC columns separating many very different types of […]

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Policy on verifying a new Cogent HPLC column’s performance

When you first receive a Cogent™ HPLC column, its performance should be checked by running a quick test to measure peak symmetry and efficiency. The column you purchased came with a Packing Test Chromatogram that shows the original QC values (peak shape, plate count) of test solutes under specified conditions. When you follow the conditions in that test […]

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What are inosine nucleotides?

All nucleotides are are comprised of the following sub-structures: A nucleobase, a 5-membered ring sugar unit (either ribose or 2-deoxyribose), and one or more phosphate groups. In the case of inosine nucleotides, the nucleobase is hypoxanthine. When a ribose unit is attached to hypoxanthine via a β-N9-glycosidic bond, it is known as the nucleoside inosine. It is the presence of […]

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What are some examples of third-party journal articles that feature the Cogent™ HPLC columns in metabolomics studies?

There are many examples of the Cogent™ HPLC columns used in metabolomics research, which have been published by third-party researchers in peer-reviewed scientific journals. Two notable works are described here. The first one, performed by Dr. Kyu Rhee and co-workers of Weill Cornell Medical College, uses the Diamond Hydride™ column to understand the pathogenic mechanism […]

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What is a “direct silicon-carbon bond” regarding Cogent HPLC columns?

For chemical bonds in traditional, ordinary type B silica based materials, the organosilane starting material is Si-O-Si-C and this reagent is reacted with the silica to form the final stationary phase which includes a Si-O-Si-C ligand. This is in contrast with the Cogent TYPE-C™ phases in that the Si-C bond is formed directly as part of the […]

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What is a Base-Deactivated HPLC Column? FAQ

“Base-deactivated” means that the Column is designed for analysis of Basic Compounds. Conventional Columns Based on Type B Silica typically have Si-OH groups on the surface that interact with bases. This Secondary Retention Mechanism is typically Undesirable and causes poor Peak Shapes. The following are two ways that Reversed Phase HPLC columns can get around […]

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What is ANP or Aqueous Normal Phase?

Aqueous normal phase chromatography (ANP) is a chromatographic technique which encompasses the mobile phase region between reversed-phase chromatography (RP) and organic normal phase chromatography (ONP) used mainly to separate polar compounds such as acids, bases and peptides.. Using a hydrophobic stationary phase such as silica hydride (available as Cogent TYPE-C™ HPLC columns) a mobile phase of 98% organic […]

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What is Aqueous Normal Phase (ANP) and how can it help you? Wikipedia Article.

Aqueous normal phase chromatography From Wikipedia, the free encyclopedia Aqueous normal phase chromatography (ANP) is an HPLC technique which encompasses the mobile phase region between reversed-phase chromatography (RP) and organic normal phase chromatography (ONP) and is used mainly for polar compounds. In normal phase chromatography, the stationary phase is polar and the mobile phase is nonpolar. In […]

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What is the most effective way to clean HPLC columns after or before use?

Many commonly used cleaning methods feature a strong wash solvent, run isocratically in order to elute strongly retained compounds or residual solvents from the column. After some time of washing in this manner, the stationary phase is essentially in equilibrium with the wash solvent, so it may still take a long time to remove contaminants from […]

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When should I use temperature in HPLC method development?

Column temperature* is a useful but often overlooked variable in HPLC separations. In reversed phase (RP), retention generally decreases with increasing temperature. For this reason, higher temperature can often be successfully used to speed up a method’s run time. Furthermore, solvent viscosity decreases at higher temperatures, so pressure is lower and this allows for higher flow […]

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