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TYPE-C Column Information

16 How to change HPLC columns from Reversed Phase to Normal Phase mode and vice versa.

To start work in normal phase mode, a simple switching procedure is recommended. A simple 30 minute procedure allows switching from one mode to another. Procedure: A – moving from Reverse Phase to Normal…

17 How to condition Cogent TYPE-C HPLC Columns for storage.

Storage Solvents for Reverse Phase (RP) or Aqueous Normal Phase (ANP): If RP and ANP are your desired next use for these columns, storage in a mixture of 40% Distilled Water that is acidified with 0.1%…

18 Literature References for Cogent UDC-Cholesterol™ HPLC Columns

The following is a list of articles published in peer-reviewed journals and books that discuss Cogent UDC-Cholesterol™ based materials and their applications: Authors Title Publication Date Volume Pages…

19 NMR Structure confirmation data for Cogent Bidentate C18™ phases

The following solid state CP-MAS 13C NMR spectrum was recorded for a Cogent Bidentate C18™ stationary phase in order to elucidate the structure. The assignments for the different carbon groups are shown…

20 NMR Structure confirmation data for Cogent Bidentate C8™ HPLC phases.

The following solid state CP-MAS 13C NMR spectrum was recorded for a Cogent Bidentate C8™ stationary phase in order to elucidate the structure. The assignments for the different carbon groups are shown…

21 NMR Structure confirmation data for Cogent UDC-Cholesterol™ phases

The following solid state CP-MAS 13C NMR spectrum was recorded for a Cogent UDC-Cholesterol™ stationary phase in order to elucidate the structure. The assignments for the different carbon groups are…

22 On-column hydrolysis in HPLC columns and what causes it? What will be the effect on Cogent TYPE-C™ Silica columns.

Hydrolysis is a common degradation mechanism, which is facilitated by the presence of acids or bases in solution or on the surface of solids the liquid is in contact with. With solids in contact with…

23 Retention and/or peak shape for citric acid has changed compared to data from a previous HPLC run. What happened?

Citric acid analysis using LCMS can be compromised due to the presence of iron in the system. When iron is present, it can cause peak distortion for compounds like this. A possible solution to this problem…

24 Retention time vary from instrument to instrument

To obtain the same retention times for analyzed compounds as in application note gradient conditions have to be adjusted according to the instrument used. Each instrument has different plumbing (dimensions…

25 Sample Diluents should match your mobile phase.

For best results, it is always best to try to dissolve your target in as close as possible to your isocratic eluent or the start of your chosen gradient. If this is not possible gradually increase the…

26 Silicon carbon bonds for Cogent TYPE-C HPLC columns.

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…

27 Tandem LCMS approach to Metabolite Profiling Presented at Metabolomics Society 2010

A poster was presented at the Metabolimics Society meeting in Amsterdam, June 2010 on a powerful way of profiling metabolites. Below is the introduction from the poster or you can download and view the…

28 Tips on solving baseline problems in ANP with the Cogent Diamond Hydride

When using a gradient method with the Cogent Diamond Hydride™ column, an inconsistent baseline may be observed in some instances. The following are some possible causes of the issue along with suggestions…

29 Using different Cogent™ HPLC stationary phases for different selectivity.

Each of the Cogent™ stationary phase materials has a different bonded ligand and therefore potential for different selectivity of given analytes. Consider the example, featuring the Cogent Bidentate…

30 Using temperature changes for separations of terpenoids with the Cogent Bidentate C18 and Cogent UDC-Cholesterol HPLC columns

Temperature is a useful variable to consider in HPLC separations. Control of temperature can reduce run times, alter selectivity, and change analyte efficiency. In this study of three terpenoids (bexarotene,…

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