Page 24 - Phytochemistry -1 (PG404) / Clinical Pharmacy 2nd level students ( 2019 )

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

5. Ruthenium test: Red colored particles (due to its
mucilage content).

I. Titermetric methods

1. Cupper reduction method

This method can be applied for

All reducing sugars:

• All monosaccharide: EX: Glucose; Fructose; galactose, mannose---

• All reducing disaccharides: EX: Lactose & Maltose

Principle

• This method is based on the reduction of known volume of
'
standardized Fehlings solution by titrating it directly against the
reducing sugar solution.

• Such sugars are capable of reducing copper sulfate in hot alkaline
medium to cuprous oxide, which forms a red precipitate and the

blue color of the solution disappear.

Procedure

1. Take 5 ml each of standard Fehling's solutions A and B into a 250 ml
conical flask, then add 40 ml water and boil gently over a small flame.

2. Place the sugar solution in a burette and titrate against the boiling
Fehling's solution, adding 1 mi of the sugar solution at a time bringing the
solution to boiling after each addition (without removing the flame).

3. Continue adding the sugar solution in 2 ml aliquots till the blue color
of the mixture disappears, then add 4 drops of methylene blue indicator

and continue titration drop-wise. The end point is reached when the blue
color of the indicator disappears. Read the number of mls of the sugar
solution used in this titration. This preliminary result is an approximate
one.

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