basic method of extraction of alkaloids

1. EXTRACTION
OF
ALKALOIDS

2. STAS-OTTO METHOD
•The technique involve the
distribution of alkaloidal bases
between acid or aqueous solution
and immiscible organicsolvent.
MethodI:

3. A) stage1:--Powdered material is moistened with water
and mixed with alkali like sodium &potassium carbonate
,ammonia, lime.
Concept :--Lime(calciumhydroxide),combines with acid ,
tannins, and other phenolic substances andsets 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 withother
substances soluble insolvent.
 Stage3:--agitate the chloroform soln. With successive
portion of dil.Sulphuric acid separating the aqueouslayer
before adding the next portion ofacid.
Concept :-the alkaloids are converted into alkaloidal
sulphates, which being soluble in water,pass intoaqeous
layer.

5.  Stage4:--Make the mixed aqueous liquidalkaline
with ammonia, collect the precipitate that forms,
wash with water anddry.
Concept :-Ammonia decomposes the alkaloidal
sulphates forming ammonium sulphates ,solublein
water ,and the free alkaloid which being practically
insoluble in water isprecipitated.

6. LOGO
Powdereddrug Containingalkaloidalsalts
• Exhaust with org. Solvent like
CHcl3, ether
• Total extracts
• Conc. & Shake with acid like
dil. H2so4
Freealkaloids
Residual organicfraction
(Pigments, fats & weak
bases or chloroform soluble
alkaloidssulphates)
organic soln (alkaloidalbases)
Moisten & render alkaline
with Na2CO3, lime, NH3
Defatted if
necessary
Aq.Acidsoln
(Alkaloidal salts)
Make alkaline
extract with
immisicible solvent
Residual aq. Fraction
Remove solvent
crudealkaloidalmixture

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.