I tried running column chromatography of my flavonoid extract using chloroform. I tried wet packing using chloroform and and while i was washing the column with chloroform, i noticed that the flowing stopped and the silica gel inside the column was cracking even though there was sufficient solvent on the top. has it got anything to do with temperature? The room temperature was 32 degrees.
First dry the silica gel with the system and try before filling the column with silica gel.
Did you use cotton plug and sand at the bottom of your column?
Dip your Silica and cotton overnight then pack your column. Overnight silica will remove the air from it. Cracking problem will be avoided.
In your case, if you have not seen any air bubble during packing, the cracked column will be packed properly when it get saturated. So keep running the column till it get saturated.
thank you very much for your response. I did not consider the issue of saturation. I packed almost immediately. I hope to retry the process again
I have made a slurry now, and i intend to leave the silica gel slurry in excess chloroform for 3 hrs before packing it into the column. I hope it is ok?
I agree with Professor Teodoro. It's always better to make slurry of silica and then pour it in the column. You can use slight pressure to settle down the silica. I don't think temperature is a problem.
what you are seeing is normal and is due both to air trapped in silica and to polar interreactions of silica with the small polarity of chloroform (dipole ca 1.0 D) which leads to local tempareture increase (you can feel it with your hand while the at first solvent front proceeds through silica)... and ultimately to initial silica cracking. But is not a prob you can either (generally preferable) make a slurry and pour it in the column avoiding this effect or just keep flushing solvent through the dry silica until effect will eventually disappeare .... Also depending on the type of eluent you use (you are right !) high temperatures in lab (30 o more celcius degree) can cause silica cracking just for solvent evaporation in silica (often seen with ethyl ether) .
Hope that could be useful
regards
Giuseppe
It is prefered to make a slurry from silica gel at first and then pour it in the column with knocking to avoid formation of air space that form cracking of silica inside column then dissolve your material in chloroform and pour it above silica gel and start your separation
Hi I just tried to use chloroform for separation of my compounds using Silica gel
I noticed just I put the chloroform the silica was dissolved
First dry the silica gel with the system and try before filling the column with silica gel.
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