Can I use acetone as a mobile phase solvent in ANP?

If you are using LCMS, the simple answer is yes but pH is also something to consider. Acetone has a high UV cutoff and therefore can be a problem for UV detection. However, this is not a problem when using LCMS or ELS detectors such as the Corona CAD. You can use acetone to replace acetonitrile with the Cogent TYPE-C™ […]

Read More

Cocaine & metabolite Ecognin, HPLC column suggestion.

We are looking for a column capable of separating cocaine and its metabolites particularly Ecgonin which is very polar. The remaining metabolites (BE, EME, etc.) are less polar. The idea would be to separate all of them in one run. Any suggestion which type of Cogent TYPE-C column would be appropriate for direct injection of […]

Read More

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 […]

Read More

How To Condition Diamond Hydride Columns for use with Serum Samples.

For Serum and other biological samples, we Recommend using: Solvent A: 50% DI Water/50% Methanol (or 2-propanol) + 0.1% Formic Acid (for positive mode MS) or +10 mM ammonium acetate or formate (for negative mode MS). Solvent B: The same as you would ordinarily use. Cleaning Tip: Methanol or 2-Propanol (IPA) helps to clean the […]

Read More

How to Store and Maintain Cogent Diamond Hydride HPLC Columns.

Before the First use of the Diamond Hydride Column: 1. Condition it with 50:50 MeOH/Water for 30 minutes. Conditioning Steps – Depends on Your Samples: 1. When using urine, plasma, or other biological samples etc: A. Conditioning the Column with 80% Acetonitrile/ 20% DI water/ 0.2% Acetic Acid (or 0.1% Formic Acid) is recommended for […]

Read More

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 […]

Read More

Lower ANP retention is observed when group in compound is ionized

Question: I am analyzing S-adenosyl methionine (SAMe) with the Diamond Hydride column in ANP mode. I used a gradient with a formic acid additive and then tried an ammonium acetate additive. With ammonium acetate, I got lower retention than with formic acid using otherwise identical method conditions. I was expecting greater retention with ammonium acetate since the carboxyl […]

Read More

Main Differences Between HILIC Columns and TYPE-C™ Columns.

There are many differences between the many HILIC columns and Cogent TYPE-C™ columns but for the sake of brevity, I will only address the main differences. Similarity: The Cogent TYPE-C (Silica Hydride) HPLC Columns perform similarly to HILIC columns as far as polar compound elution order is concerned (when using higher than 70% organic composition of the […]

Read More

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 […]

Read More

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 […]

Read More

What is the carbon load of the Cogent Diamond Hydride HPLC column?

There is less than 2% carbon load on the column. However it should be noted that the carbon on this column is not directly responsible for separation. While the carbon does modify the surface and the retention character of the columns it is not involved in hydrophobic interaction and therefore not directly responsible for retention. […]

Read More

What is the solvent strength order in ANP?

In ANP, the strongest solvent is water. The order in decreasing solvent strength is: DI water > methanol > isopropanol > acetone ~ acetonitrile These are general estimates; in this comparison of acetone and acetonitrile for different amino acids, retention is somewhat comparable for some but significantly different for others. For methanol or isopropanol, these are typically […]

Read More

What Suggestions can you offer for Analysis of metabolites such as glucose, pyruvate, taurocholic acid, gamma glutamylcysteine etal.

What suggestion can you offer for Analysis of Metabolites such as glucose, pyruvate, taurocholic acid, gamma glutamylcysteine, glycochenodeoxycholate, glycerol-3-phosphate, spermidine, taurine, and S-Adenosylmethionine? Suggestion: We would recommend the Cogent Diamond Hydride™ HPLC Column for this Analysis. Many of these compounds are quite polar and would be very difficult to separate by Conventional Reversed Phase Methods. […]

Read More