Page 67 - phytochemistry general program

Separation of hyoscine from both atropine and hyoscyamine depends on the .1
difference in their basicity. Hyoscine is a weaker base. The mixture is, thus,

treated with NaHCO3 to liberate hyoscine which can be extracted with ether.
Separation of atropine from hyoscyamine is based on the difference in the .1
solubility of their oxalates in a mixture of acetone and ether and is carried as

follows:
The aqueous solution remaining after extraction of hyoscine is rendered .1
alkaline with ammonia and extracted with chloroform. The solvent is then

evaporated and the residue is dissolved in oxalic acid.
Extract with acetone-ether mixture, to separate atropine (sparingly soluble) .2

from hyoscyamine (freely soluble).

Determination of atropine, hyoscyamine and hyoscine in a mixture

The percentage of the total alkaloids (A) is determined by the normal .1
volumetric method .1
.1
The residue of crude alkaloids obtained after extraction and purification is taken
up by dilute hydrochloric acid. .1

Sodium bicarbonate is added and hyoscine (scopolamine) is extracted with .1
ether (being a weaker base than atropine and hyoscyamine, it can liberated .1

from its salt by NaHCO3) .1
The solvent is removed and the residue is dissolved in neutral alcohol and
titrated against standard acid. Then the percentage of hyoscine (B) is

calculated.
The aqueous layer remaining after separation of hyoscine is rendered alkaline

with NaOH, then extracted with CHC13, and the solvent is evaporated.
The residue is dissolved in 90% alcohol and the optical rotation of the alcoholic
solution is measured from which the percentage of hyoscyamine (C) can be

calculated (Atropine is optically inactive).
The percentage of Atropine is calculated by difference as follows:

% of atropine = A - (B+C)

Quantitative determination of solanaceous alkaloids.

A vast number of techniques have been used for the evaluation of the
tropane alkaloids in plant extracts and as pure compounds. These techniques
involve volumetric, colorimetric, photometric, potentiometric, acid-dye and

immunoassay techniques.

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