Extractionofalkaloids

basic method of extraction of alkaloids

1. EXTRACTION OF ALKALOIDS

2. STA S -OTTO ME T HOD Th e t e c hn i q ue i n v ol v e the distribution of alkaloidal bases between acid or aqueous solution and immiscible organic solvent. Method I:

3. A) stage1:-- Powdered material is moistened with water and mixed with alkali like sodium & potassium carbonate , ammonia, lime . Concept :-- Lime(calcium hydroxide),combines with acid , tannins, and other phenolic substances and sets free alkaloids . B). Stage2:-- extract the free alkaloids by hot continous percolation with chloroform or any other organic solvents.

4. Concept :-the free alkaloids dissolve together with other substances soluble in solvent. Stage3 :-- agitate the chloroform soln. With successive portion of dil.Sulphuric acid separating the aqueous layer before adding the next portion of acid. Concept :- the alkaloids are converted into alkaloidal sulphates, which being soluble in water,pass into aqeous layer.

5. Stage4 :--Make the mixed aqueous liquid alkaline with ammonia , collect the precipitate that forms, wash with water and dry. Concept :- Ammonia decomposes the alkaloidal sulphates forming ammonium sulphates ,soluble in water ,and the free alkaloid which being practically insoluble in water is precipitated .

6. LOGO Powdered drug Containing alkaloidal salts Exhaust with org. Solvent like CH cl 3 , ether Total extracts Conc. & Shake with acid like dil . H 2 so 4 Free alkaloids Residual organic fraction (Pigments, fats & weak bases or chloroform soluble alkaloids sulphates ) organic sol n ( alkaloidal bases) Moisten & render alkaline with Na 2 CO 3 , lime, NH 3 Defatted if necessary Aq. Acid sol n (Alkaloidal salts) Make alkaline extract with immisicible solvent Residual aq. Fraction Remove solvent crude alkaloidal mixture

7. Method I I : The powder is extracted with water soluble organic solvents such as MeOH or EtOH which are good solvents for both salts and free bases . And the resultant extract is submitted to same process as that of method I .

8. PURIFICATION OF ALKALOIDS :: 1.DIRECT CRYSTALLISATION FROM SOLVENT. 2 . STEAM DISTILLATION . 3. CHROMATOGRAPHY TECHNIQUES. 4 . GRADIENT pH TECHNIQUES.

9. GRADIENT pH TECHNIQUES : Though alkaloids are basic in nature, there are variations in the extent in the basicity of various alkaloids of the same plant. Depending on this character pH of the aqueous solution is increased gradually by 0.5 increment upto pH 9 , and extraction is carried out at each pH level with organic solvent, by this way alkaloids with different basicity are extracted.