I am extracting alkaloids by the method of Maldoni, 1991. After isolation of tertiary alkaloids I had to isolate Quaternary Alkaloids (QA). It is obvious that if the QA is not present in that plant, so it will not available to get precipitate. However, I have isolated QA form the same plant previously. Again, One mistake I have did that is, I made the extract (which was pH 10) to pH 1, again I raised it to pH 12 and then to pH 2.3. Actually, in literature, there is mentioned to decrease pH from pH 10 to pH 2-2.5 only.
How do I get my QA?
adjust pH 2.3 directly and avoid rinsing in pH 12 and pH 1 solution.
Thank you Sheeraz,
Actually, I have the plant extract which was already gone through much pH variations (first pH1 and then pH 12), and afterward, I made it to pH 2.3 to get QA? But the results was showing no precipitation with QA. Now what to do? As, I mentioned, I got QA from same plant previously.
1- Try to add edge of an ammoniac solution in your plant crushed by thoroughly mixing all well then extracted by methanol (PH 10 ), then filter to obtain the methanol extract .
2- evaporated methanol and add to your extract a methanol / water solution HCl (PH 2-4) / dichloromethane.
3- Mix and decanted to separate the dichloromethane solution and dichloromethane and evaporate.
4- your dichlorométhnique extract obtained will be used to separate your alkaloids by CC.
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