I used column chromatography packed with silica as a stationary phase, then sub-column chromatography. The end resulted in a mix of 2 triterpenes (few of them), and regrettably there is no chemical review available for the palmae family.
I already separated a mix of 2 triterpenes from the palmae family and they are very closely related in Rf but I couldn't separate each one as pure. What can I do to separate a pure compound? Why do triterpenes appear as an oily composition at room temperature?
Dear Shrouck, most of triterpenes are oily compounds at room temperature. Column chromatography is used to separate the mixtures. Try with different ratio of solvents as mobile phase. Start with non polar solvent. or we can proceed with preparative TLC.
Dear Shrouck, these triterpenes may be the positional isomers, in which only the position of the groups is changed. The resolution of such triterpenes is difficult but can be dealt with the derivatisation approach. These triterpenes mixture can be derivatised and then it can be column chromatographed to get pure compounds. The another approach may be to modify the mobile phase of column chromatography as stated above by Jawla Sunil. There are reports in the literature for Ursolic acid and Oleanolic acid separation by modifying the mobile phase with the B-cyclodextrin as a modifier. Though it is used for the analytical resolution, the approach can also be applied at the preparative scale.
Dear Shrouk, you can see the research article attached for the reference.
dear Shrouk Hussein you can used different mesh size silica gel. for better sepration viz. 60-120, 70-200, 200-400 mesh size. for better result use 200-400 mesh size. also use long column havin length greater than 100 cm and diameter greater than 50mm. used different solvent in order of increasing polarity for elution. i.e. starting with hexane, hexane-chloroform, chloroform, chloroform-ethylacetate, ethylacetae, ethylacetate-methanol etc.......
Dear Shrouk,
all the above mentioned instructions may help to separate your triterpenes, so there is almost nothing to add.
But, could you not test another adsorbent, different length of the column, lower/higher temperature /using fridge or thermostat/ of separation, and as mentioned by the authors before me - different polarity mobile phases.
It strikes me, what about the use of Al2O3 as a sorbent.
Regards,
R.S.
Dr: R.S,
No, i don't test another adsorbent
thanks for mentioned a different way to separation
Dear Shrouk,
I think you may use semi-prepared HPLC with a CAD detection to get purified compound from mix triterpene from yeast or plant extraction.
The simplest possible way to do is prep-TLC its effective and simple and you can preapre this plate by self.
also try with two dimention TLC and its more useful for resolve componant spot
After developing the chromatogram, turn the TLC plate 90o and increase the polarity of the solvent system by few drops of acetic acid (glacial)
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