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1 A case to eliminate retention time drift in ANP using the Cogent Diamond Hydride in LCMS.

We had a significant run to run RT drift ( up to 1 min for 10 repeated runs) using the Cogent Diamond Hydride™ HPLC column we ordered two weeks ago. After conditioning the column with 90% IPA and 10X…

2 Acetone as the Organic Mobile Phase Component in LCMS.

“Green” substitute for separation of amino acids Caution: Acetone and Amines can react When working with Acetone as an HPLC solvent it is important to note that primary amines could react with Acetone…

3 Acid Washing RSA Vials has consequences

Q. What are the advantages and disadvantages of acid washing RSA Vials? A. There is no reason to acid wash RSA vials. The main reason to acid wash vials is to reduce adsorption due to native silanols…

4 Activity in HPLC. Simple and easy definition.

It is the relative strength of the surface of the stationary phase in adsorption chromatography. In the case of silica gel, the more silanol groups are available on the surface, the more active it is.…

5 Adjusted retention time in HPLC. A Primer.

Adjusted retention time (tR') is the retention time adjusted for the hold-up time: tR' = tR - tM where tR is the retention time and tM is the hold-up time. The hold-up time is the time of an analyte (small…

6 ANP v. HILIC when using Ballistic Gradient HPLC or LCMS.

In comparing ANP vs. HILIC, the former has an advantage in using ballistic gradients because HILIC is generally not suitable for these types of gradients. The reason is the semi-permanent water layer…

7 Aqueous Normal phase (ANP) defined & compared to Reversed Phase & Normal Phase in HPLC

Aqueous Normal Phase (ANP) is probably the newest HPLC technique or at least the latest to be investigated well. Often we are asked what is ANP. Below is a link with more explanation than this article…

8 Aqueous Normal Phase (ANP) HPLC retention mechanism elucidated.

The mechanism of aqueous normal phase (ANP) retention is an active area of investigation. However, much progress has been made in recent years at elucidating how polar compounds are retained by this mechanism…

9 Assuring retention of polar compounds in an ANP gradient in positive mode LCMS.

When using a Cogent Diamond Hydride™ column prepare your solvents for positive ionization in LC-MS: Solvent A: 50% methanol/50% DI water + 0.1% formic acid and Solvent B: 90% acetonitrile/10% DI water/0.1%…

10 Autoclaving Glass Inserts with plastic feet is not recommended.

Autoclaving glass or plastic inserts with attached plastic springs is not recommended. While the glass can withstand temperatures up to 1,000°F, the polyetheylene spring will become deformed, may crack…

11 Blocked TYPE-C HPLC Column from proteins that were in the sample matrix can be recovered: Tip.

It is of crucial importance to always filter your samples prior to introduction to an HPLC instrument. Most samples will contain particulates and other matrix components that can cause blockages in the…

12 Calculating relative response factor (RRF) on different instruments/detectors

The RRF value you calculate should be the same, irrespective of the instrument or detector used, as long as linearity has been demonstrated on all the involved instruments/detectors. © Copyright MicroSolv…

13 Calculating Theoretical Plates N half height. Simple and easy definition.

The theoretical plate number N0.5 can be calculated from a chromatogram using the equation below: N 0.5 = 5.54 (t R /w 0.5 )2 Where tR is retention time and w0.5 is the peak width at half its height.…

14 Can ANP chromatography be used to retain steroids by HPLC or LCMS?

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…

15 Can Cogent TYPE-C HPLC Columns be used in supercritical fluid chromatography (SFC)?

As far as compatibility in SFC is concerned, the answer is yes. These columns are fully compatible with the typical conditions used in an SFC application and the packing material and hardware will not…

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