Page 35 - Phytochemistry -1 (PG404) / Clinical Pharmacy 2nd level students ( 2019 )

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

ESTIMATION OF A MIXTURE OF

GLUCOSE, FRUCTOSE AND SUCROSE

1. To estimate the percentage of the total reducing sugars (glucose and

fructose) apply to the fore mentioned copper reduction method. Pill the
burette with the sugar solution and Fehling's solution as before.

2. To estimate the percentage glucose (aldose) only: Titrate another
portion of the mixture with 0.1 N I 2 solution following the fore
mentioned-iodometric method.

3. Calculate the Percentage of fructose (ketose) by subtracting the result
obtained in (2) from that obtained in (1).

4. To estimate the percentage of sucrose, apply the method mentioned
before for non-reducing sugars. In this case, the result corresponds to the
original glucose and fructose in addition to the invert sugar (resulting

from the hydrolysis of sucrose).

5. Subtracting the result obtained in (1) from that obtained in this

estimation gives the Invert sugar only.

In this estimation take 20 ml of the mixture and add 5 ml of concentrated
hydrochloric acid. Heat on a water-bath for 15 min at 70°C. Cool and

neutralize with sodium carbonate. Make up to 200 or 250 ml, in a
measuring flask a titrate against Fehling's solution in the usual way.

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