I have synthesized compound which contains amide bond, in column chromatography this compound sticking to silica? Is the use of alumina in place of silica resolve this problem?
< "if the compound are sticking to silica" > Does "sticking" mean that the compound is well retained on the column and it does not elute? If so, please specify the exact type of LC column/support (with dimensions and flow rate) and mobile phase. This sounds like a simple method development problem and changing the mobile phase (% composition, pH...) to change the retention of the sample on the column is part of that process. That may be all there is to it.
We really need far more information about your sample and its solubility to answer the question, but let's think about the general differences between silica and alumina phases.
- Silica phases tend to be acidic, less polar and retain basic samples.
- Alumina phases tend to be basic, more polar and retain acids better.
So based on this info, if the compound is well retained on silica, than switching to alumina may indeed retain it much less. BUT, this is not how we perform LC method development. Retention is a good thing. No retention is a bad thing. So, yes, you can try an alumina phase as it may provide less retention than a silica phase, but I would also suggest thinking about the properties of the sample first and determining which mode is more appropriate.
"alumina can be used in place of silica as a stationary phase if the compound are sticking to silica ?" Perhaps - try it and see
"Is the use of alumina in place of silica resolve this problem?" Perhaps - try it and see
There no substitute for learning from experimental work.
< "if the compound are sticking to silica" > Does "sticking" mean that the compound is well retained on the column and it does not elute? If so, please specify the exact type of LC column/support (with dimensions and flow rate) and mobile phase. This sounds like a simple method development problem and changing the mobile phase (% composition, pH...) to change the retention of the sample on the column is part of that process. That may be all there is to it.
We really need far more information about your sample and its solubility to answer the question, but let's think about the general differences between silica and alumina phases.
- Silica phases tend to be acidic, less polar and retain basic samples.
- Alumina phases tend to be basic, more polar and retain acids better.
So based on this info, if the compound is well retained on silica, than switching to alumina may indeed retain it much less. BUT, this is not how we perform LC method development. Retention is a good thing. No retention is a bad thing. So, yes, you can try an alumina phase as it may provide less retention than a silica phase, but I would also suggest thinking about the properties of the sample first and determining which mode is more appropriate.
I would like to recommend ordinary RP-HPLC column (sufficiently end-capped such as Macherey-Nagel, Düren, Germany and/or Nomura Chemical, Seto-city, Aichi, Japan). Please use 0.1 M acidic phosphate (adjusted to pH 2.0 by adding 7 mL/1 L) as solvent A (please see file; Lysozyme RP-HPLC).
Dear Nilesh ,
If your compounds contain more baisc groups such as amide bonds, guadinium groups then it is very difficult to elute pure compound using silica gel as a stationary phase, if you are using manual columns. Earlier i faced this type of problems. you can try first acidic alumina then neutral alumina and in last basic alumina. In my case i was successfully separate my desired compound as a single spot on neutral alumina.
I think, it will helpful in your case also.
Good Luck.
What solvents did you use on the silica? One can used methanol and even water on silica so long as the solvent system is kept neutral.
Alumina can also work, and can run polar solvents as well.
One can use HILIC even for flash chromatography with bare silica and other column packings.
http://www.teledyneisco.com/Documents/Liquid%20Chromatography/Application%20Notes/HILIC%20Purification%20Strategies%20App%20Note.pdf#search=HILIC
http://www.teledyneisco.com/Documents/Liquid%20Chromatography/Application%20Notes/RediSep%20Rf%20Gold%20Silica%20and%20Highly%20Polar%20Solvents%20App%20Note.pdf#search=HILIC
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