Extraction

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Chapter: Pharmacognosy and Phytochemistry : Drugs Containing Alkaloids

The extraction of alkaloids is based on their basic character and solubility profiles. Generally alkaloids are extracted mainly using two methods....


EXTRACTION

 

 

The extraction of alkaloids is based on their basic character and solubility profiles. Generally alkaloids are extracted mainly using two methods.

 

 

Method A

 

The powdered material that contains alkaloidal salts is moistened with alkaline substances like sodium bicarbon-ate, ammonia, calcium hydroxide, etc., which combines with acids, tannins and other phenolic substances and sets free the alkaloids bases. Extraction is then carried out with organic solvents such as ether or petroleum spirit. The concentrated organic liquid is then shaken with aqueous acid and allowed to separate. Alkaloid salts will be present in aqueous liquid, while many impurities remain behind in the organic liquid.

 

Method B

 

The collected powdered material is extracted with water or aqueous alcohol containing dilute acid. Chloroform or other organic solvents are added and shaken to remove the pigments and other unwanted materials. The free alkaloids are then precipitated by the addition of excess alkalis like, sodium bicarbonate or ammonia and separated by filtration or by extraction with organic solvents.

 

Volatile liquid alkaloids (nicotine and coniine) are isolated by distillation. The powdered material that contains alkaloids is extracted with water and the aqueous extract is made alkaline with sodium carbonate or ammonia and the alkaloid is distilled off in steam. This could be collected and purified.

 

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