Page 33 - Phytochemistry -1 (PG404) / Clinical Pharmacy 2nd level students ( 2019 )

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

Notes on the procedure:

Heating sucrose solution with hydrochloric acid results in the production
of invert sugar. This may be represented in the following:

C12H22O11 + H2O C6H12O6 + C6H12O6

Sucrose Glucose
Fructose

342 g 180 g 180 g

1g of glucose corresponds to 342/360 = 0.95 sucrose

For calculation: for example if the invert sugar solution taken in the
titration (resulting from the hydrolysis of sucrose) to reduce 10 ml of

Fehling's solution is 15 ml, this means that this volume contains 0.05 of
invert sugar (glucose + fructose).

To calculate the percentage of sucrose in the original sample we have to

multiply the figure obtained by 100/volume of sample taken (20 ml)

100 X 0.05 X 0.95

Percentage of sucrose =

1.5

Estimation of a mixture of Glucose and Fructose

Principle:

Glucose can be determined by iodometric method, which is useful for
aldoses b not for ketoses, but fructose can be estimated through the
copper reduction method which give the total sugar of glucose and

fructose. Then the fructose is determined after simple calculations.

Procedure:

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