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1 How can I purge metals from my HPLC system using EDTA?

In LC-MS, metal ions can be responsible for distorted analyte peak shapes via chelating. If you determine that this is the cause of a peak issue, here is what you can do to eliminate metals from the system…

2 How can I separate phenylephrine HCl, acetaminophen, and dextromethorphan?

The Cogent Phenyl Hydride™ would be recommended for these compounds because of the dextromethorphan. It has a strong tendency to tail on most columns but the Phenyl Hydride™ column and can produce…

3 How do I calculate assay of lisinopril dihydrate based on the anhydrous form?

When you weigh your reference standard and use the mass in the assay calculations of your formulation, you must correct for the water since the reference standard is the dihydrate form. You know the molecular…

4 How do I condition Diamond Hydride columns when I use them for 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) or +10 mM ammonium acetate or formate (for negative…

5 How do I determine concentration of an impurity when I know the relative response factor (RRF)?

The concentration can be calculated once you have values for the following two equations: Response Factor (RF) = Peak Area / Concentration Relative Response Factor (RRF) = RFimpurity / RFAPI You can use…

6 How do I measure signal-to-noise ratio in a chromatogram?

The best way is to zoom in on the peak of interest using your data analysis software so that the baseline near the peak is also visible as well. Depending on how sharp or narrow your peak is, you'll want…

7 How to Calibrate UV-vis and HPLC Detectors with NIST Traceable Solutions Below 230nm

Holmium Oxide is an internationally recognized wavelength calibration primary standard, supported by NIST and other standards organizations. It provides 14 official absorbance bands ranging from 241 nm…

8 How to change columns from reversed phase to normal phase mode and vice versa

Just as a reminder, all Cogent TYPE-C™ columns are filled with water containing solvents during shipping. To start work in normal phase mode, a simple switching procedure is recommended. A simple 30…

9 How to change ferrules on HPLC column connectors

HPLC Column Connectors So Easy... Anyone Can Use It! Ferrule Replacement Instructions for the HPLC Column Connectors Change ferrule after approximately every 50 insertions or when excessive ferrule wear…

10 How to choose a Cogent HPLC column for an application

The first thing to consider is the chemical structures of the analytes in your sample and the corresponding most suitable retention mode for them. For reversed phase, the general order of stationary phase…

11 How to clean sparging stones and inline SS filters.

Inlet stainless steel filters or sparging stones can be cleaned by ultra-sonication in 30% phosphoric acid, clean afterwards with DI water (ultra-sonication) and Methanol (ultra-sonication). Same would…

12 How To Condition 47mm Nylon Membranes for Use with the Mobile Phase Filter Degasser...

Filter membranes with smaller pores sizes such as 0.45µm have higher bubble points (the differential pressure required to draw air through a wet membrane). The bubble point is a function of the pore…

13 How to Condition a CEC Column

It is very important that you condition the capillary properly before using it. DO NOT CONDITION YOUR COLUMN LIKE A CE COLUMN: IT WILL BE DESTROYED. Instructions for Conditioning and Installation of Milli-phase…

14 How to Condition a CelerityCE™ Column

View information about CelerityCE capillaries It is very important that you condition the capillary properly before using it. DO NOT CONDITION YOUR COLUMN LIKE A CE COLUMN: IT WILL BE DESTROYED. Instructions…

15 How to Condition CE100-SA Controlled & Zero EOF Capillaries For CE

Capillary Conditioning Procedure: Never Use Strong Bases on these Capillaries Carefully remove the capillary from the shipping/storage container. Remove protective polyimide coating by using 98% fuming…

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