Page 47 - Phytochemistry -1 (PG404) / Clinical Pharmacy 2nd level students ( 2019 )

Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

COLORIMETRIC ESTIMATION OF DIGITALIS GLYCOSIDES
BY BALJET'S REAGENT

Principle:
It depends on measuring the absorbance or % transmittance of
orange red color produced by reaction of purified digitalis extracts with
Baljet’s reagent (95 ml 1 % picric acid + 5 ml 10 % NaOH).

Reagents
− Ethanol 70%
− Lead acetate solution, 12.5 % w/v
− Disodium hydrogen phosphate solution, 4.7 % w/v.
− Picric acid solution, 1% w/v
− Sodium hydroxide solution, 10 % w/v

− BaIjet's reagent: 95 ml of picric acid solution and 5ml of sodium
hydroxide solution (freshly prepared just before use).

Preparation of the tincture of Digitalis

Weight accurately about 10g of Digitalis leaf in moderately fine
powder, transfer to a stoppered flask and add 100 ml of ethanol 70%. Shake
gently, for one hour, allow standing for 24 hours and filtering rapidly.
Prepare the tincture from standard Digitalis powder in the same way

Purification of the tincture and color reaction

1. From the prepared tincture of Digitalis leaf, take an aliquot of 2 ml,
while from the tincture of the standardized Digitalis powder take two
aliquots of 2 ml and 1 ml respectively, and transfer each aliquot to a 25
ml volumetric flask containing 15 ml of distilled water.
2. Treat each solution with 2 ml of freshly prepared 12.5% solution of
lead acetate.
3. Adjust the volume to 25 ml with distilled water and filter through
Whatmann No. I filter paper.
4. Transfer 10 ml of each filtrate to another 25 ml volumetric flask, add 2
ml of 4.7 % solution of disodium hydrogen phosphate and complete to
25 ml with distilled water.
5. Mix the contents of each flask and then filter through Whatmann No.
1 filter paper. Clarify the filtrate again by filtration through a sintered

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