Page 72 - Phytochemistry 2 (06-PG 605)

Separation of a mixture of atropine, hyoscyamine and
hyoscine

1 Separation of hyoscine from both atropine and hyoscyamine
depends on the 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.

2 Separation of atropine from hyoscyamine is based on the
difference in the solubility of their oxalates in a mixture of
acetone and ether and is carried as follows:
a- The aqueous solution remaining after extraction of hyoscine
is rendered alkaline with ammonia and extracted with
chloroform. The solvent is then evaporated and the residue
is dissolved in oxalic acid.
b- Extract with acetone-ether mixture, to separate atropine
(sparingly soluble) from hyoscyamine (freely soluble).

Quantitative determination of solanaceous alkaloids

Estimation of pure alkaloids
Pure alkaloids are evaluated by:

1- Colourimetric method
Atropine gives violet colour with Vitali-Morine’s reagent. The

colour can be measured colourimetrically at a wavelength of 550
nm.
2- Non-aqueous titration

Atropine, hyoscyamine and hyoscine and their medicinal
preparations are estimated potentiometrically and/or by non-
aqueous titration.

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