I am trying to isolate alkaloids from spinach. I am having methanol extract. I am planning to do 5% citric acid-ethyl acetate partition followed by addition of ammonia and extraction with ethyl acetate. Is that correct or I can try butanol also in both the steps? Please help me with your expertise. Thanks.
That should work because you are making a salt and dissolving it into water, then moving the free base back into organic solvent. I've done similar extractions but using methylene chloride for the organic layer and hydrochloric acid for the acid.
IMO, I'd prefer not using butanol because it has a high boiling point and tends to carry over a lot of water (and probably some of the ammonium citrate that you will create). If I needed to use butanol, I'd consider either acetic or formic acid instead of citric acid because the ammonium salts of these acids are volatile.
Another way to capture alkaloids is via ion exchange columns (strong cation exchange)- links below.
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN40_Purification_of_Alkaloids_with_RediSep_Rf_SCX_Columns.pdf
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN98_Hints%20for%20Strong%20Ion%20Exchange%20Resins.pdf
Dear Prof. Philip,
Alkaloids were reported from Portulaca oleracea (http://www.sciencedirect.com/science/article/pii/S0031942205004176). I am also working on similar kind of edible greens which is used in cookery in India. I have done preliminary tests. I am getting positive results with Dragendorff's reagent. Can I proceed further? Please help me with your suggestions.
Dear Prof. Jack,
I read your answer in RG. If I use acidic methanol, what is the solvent I have to use for Partition? Thanks.
@ Govindarajan Prasanna - I think you are asking about acidic methanol for extracting the alkaloids from spinach? If so, dry it down and partition as you mention above.
If you mean acidic methanol on the ion exchange columns (links in my earlier reply), the extract is dissolved in acid to ensure the alkaoids are ionized so they interact with the ion exchange column. Afterwards, the column is washed with an acidic solvent as the protons displace some of the alkaloids. I then run another gradient with under basic conditions. The pH converts the alkaloids to free-bases allowing then to elute, if they haven't eluted in the earlier gradient..
Dear Prof. Philip,
It was not Spinacia oleracea. Thank you for your comments.
Dear Prof. Jack,
Thank you. Hope to get purified alkaloids by this method.
Hi,
you could try the procedure described in the attached file. It is an effective procedure established in our lab years ago and used till now for alkaloid extraction and purification.
Good luck,
Andrey
Yes do any specific chromatographic techniques, either ion exchange or size exclusion
If you've got a marker alkaloids, it will be easier, if you are still exploratory, try before you do identify with TLC spray reagent then sprayed dragendrof, if it gets alakaloid marker, you can using current TLC Prepararatif to take its compounds
I am agreeable with Muhammad Taufik..use dragendrof as alkaloid marker in TLC ,scale to preparative plates, scrap off the positive bands and repurify with column chromatographic methods. Good luck
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