To determine the total Alkaloid Content

Experiment

 DETERMINATION OF TOTAL ALKALOIDS

Object: 

To determine the total alkaloid content of cinchona extract.

Requirements:

Chemicals: chloroform,HCI, sodium hydroxide, alcohol, methyl red, ammonia solution.

Glassware: beaker,funnel, glass rod, separating funnel, dropper.

Theory:

Alkaloids are basic nitrogen containing compounds obtained from plants, animals and 

microorganism having a marked physiological action. Alkaloids have diverse and important 

physiological effects on humans and other animals. The term Alkaloids is derived from the 

word alkali-like and they have some of the characters of natural amines. The definition of 

alkaloid is the organic compounds from natural or synthetic origin which are basic in nature 

and contain one or more nitrogen atoms normally in heterocyclic ring and possess specific physiological action on human animal body when used therapeutically.

Alkaloids found in cinchona bark still play an important role in medicine for example 

as antimalarial and anti arrhythmic drugs. Six respective derivatives (dihydro quinidine, 

dihydro quinine, quinidine, quinine, cinchonine and cinchonidine) has been quantified in 

crude plant extract.

Total alkaloids are determined volumetrically by acid – base titration and calculated as quinine.

Determination of total alkaloids of cinchona extract:

1.Introduce 10 ml of the cinchona extract into a separating funnel, add 1N sulphuric acid (10 

ml) and water 10 ml.

2.shake with 10 ml of chloroform and allow to separate the mixture. Shake and allow to 

separate and discarded the chloroform layer.

3.Transfer the acid wash to the mother liquor and basify with about 5 ml of strong ammonia 

(test with litmus paper).

4.shake with successive portions of chloroform (30,20,20 and 10 ml). Test for completion of 

the extraction with mayers reagent.

5. wash the combined chloroform extract with 10ml of water. Transfer the extract toa 

distillation flask to remove the solvent on a boiling water bath.

6. Add 5 ml of alcohol to the residue and evaporate the alcohol on a water bath.

7. Dissolve the residue in 2 ml of chloroform and add 10 ml standard N/10 hydrochloric acid. 

Heat on a water bath to remove the chloroform and back titrate the excess acid against N/10 

sodium hydroxide using 3-5 drops of methyl red as indicator.

Calculation

Each 1ml of N/10 hydrochloric acid – 0.03091 g of quinine

Percentage total alkaloids= [ (10 ml of N/10 NaOH) × 0.0391 × 100] /10

=______ % w/v calculated as quinine

Result

The total alkaloid content of cinchona sample is________.