Chemical/Laboratory Techniques: Column Chromatography

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Column chromatography is based on the same principle as Thin Layer Chromatography ( • Chemical/Laboratory Te... ) but enables the separation of different components from a reaction mixture on a preparative scale. While using Silica or Aluminium oxide as the stationary phase (the most commonly applied), the mobile phase is an organic solvent or a mixture of organic solvents. The stationary phase consists of an adsorbing material, which is used as a powder instead of being attached to glass or aluminium foil as in TLC. The stationary phase is packed into the column and the reaction mixture is added to the top part of the packed column. By running the mobile phase (eluent) through the column, the components will elute from the column at different times. When using silica as a stationary phase, it is possible to apply (air) pressure to the column, causing the mobile phase to run faster and the chromatography to be quicker (flash chromatography).
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Пікірлер: 9

@ivanbombana7282 Ай бұрын

Components of your mixture please?

@salehchem4376 Жыл бұрын

thank you. If I used wet packing of silica gel to column (slurry), here, can I use any solvent for silica gel until reached slurried, or same mobile phase or must use only hexane.

@TjallingCanrinus 20 күн бұрын

Preferably you use the solvent you are going to use for you column. If you work with a gradient it is best to use the least polar mixture that you plan on using for pouring the column. We advice to never use n-hexane as it is highly toxic and my suggestion would be to use heptane (greenest option) or pentane (faster to evaporate).

@salehchem4376 Жыл бұрын

thank you so much. Is there standard to use silica gel in column, I mean if my sample a little bit like (0.01 gram), how much of silica gel use here? in contrast, if I have a lot of samples such as (1 gram or more), here, how much of silica gel have to use? I mean is there ratio from silica gel to sample to use in column, please tell me

@TjallingCanrinus 20 күн бұрын

As a rule of thumb you should use 30:1 ratio silica to compound if you have a good separation on TLC. If the separation is very bad you can go to 100:1. It is however also important that the column has a length of 15-18 cm. That means that the diameter of your column glassware should match the amount of used silica.

@salehchem4376 Жыл бұрын

If I have solid sample containing components, can I use any solvent to dissolve it? Or I have to use only the same mobile phase as solvent to dissolved sample? Another case, if must use same mobile phase, but my sample can not dissolve, here, please I need solution to this problem. can I use any solvent? thank you alot

@TjallingCanrinus 20 күн бұрын

If you sample is a solid add it on top of the silica, put a layer of sand and run it into the columns with a small amount of eluent (mobile phase). Then run the column with more solvent. If your sample does not dissolve in your eluent it will not run through the column, you should either change the eluent of find a different separation technique.

@ivanbombana7282 Ай бұрын

Components of your mixture please?

@TjallingCanrinus 20 күн бұрын

We used a mixture of old dyes we had, I believe it was Oil blue and Oil red. We do not have them anymore so I can't check the CAS numbers.