ESTIMATION OF SUGAR USING BENEDICT’S METHOD

ESTIMATION OF REDUCING SUGAR USING BENEDICT’S METHOD 

AIM: 
 To estimate the amount of glucose present in the given unknown solution using Benedict’s quantitative reagent. 

PRINCIPLE:
It uses Reagent called  Benedict’s quantitative  reagent which contains copper sulphate-sodium acetate and sodium carbonate. It also contains potassium thiocyanate and small amount of potassium ferricynate (prevents the pre oxidation of copper). Methylene blue will be used as an additional indicator. The reduction of Cu3+ ions by sugar is a nons tiochemetric equation and is only constant over a small range of sugar concentration. To obtain accurate results the volume of sugar added must be within 6-12ml for 10ml of Benedict’s regent.On the reduction of Cu3+ ions, which inhibits the end point of the titration digest the transition from blue to white to be readily observed.

REGENT REQUIRED:

•  2mg/ml glucose
• Benedict’s quantitative reagent (sodium citrate, potassium thiocynate ,18%  sulphate and 5% potassium ferricyanide )
• Anhydrous sodium carbonate

PROCEDURE: 

5ml of Benedict’s reagent was pippeted out into a clean conical flask. Anhydrous sodium carbonate was added to provide the required alkalinity with a few porcelain bits and heated to boiling over a moderate flame. Standard glucose solution is taken in a burette. When the Benedict’s solution boils continuously, glucose solution is added drop by drop (1 drop/sec) till last trace of blue colour disappears. The volume of glucose rundown is noted and the titrations are repeated to concordant values.  Then the burette was filled with unknown sugar solution and the Benedict’s reagent was titrated as before. The volume of sugar solution rundown was noted and titrations are repeated for concordant values. 

RESULT:

A light Green, Yellow or Brick color

-Dixy