CONCENTRATION OF
OBSERV A TIONS SUGAR IN THE CLINICAL
ORIGINAL SOLUTION EVALUATION
(%)
No colour change (Blue) 0.0% Nil
Green co loured solution with 0.1% Traces
no precipitate.
Green coloured solution with 0.1 - 0.5% +
yellow precipitate.
Olive green coloured .0.5 - 1% ++
. solution with yellow
precipitate. ..
Yellow orange coloured 1- 2% +++
precipitate.
Brick red coloured 2% or more. ++++
precipitate.
C. BARFOED'S TEST:
1. Barfoed' s Reagent:
i. Copper acetate, and
ii. Acetic acid.
2. Original solution (q.S.) - containing a carbohydrate.
. PROCEDURE:
To 5ml of Barfoed's reagent in a test tube add 0.5ml of sugar solution (original solution). Mix thoroughly and place it in the boiling water bath. Note; the time when
signs of reduction i.e., formation of a red precipitate of cuprous oxide first appears in the test
tube. .
The monosaccharides start forming precipitates in less than 7 minutes where as the precipitates appearing after 7 minutes indicate the presence of disaccharides in the solution.
05 OSAZONE TEST (PREPARATION OF OSAZONES)
REAGENTS:
1. Phenylhydrazine mixture consisting of:
i, Phenylhydrazine, and
ii, Anhydrous sodium acetate.
2. Original solution (O.S.) - containing a carbohydrate.
PROCEDURE:
Take phenylhydrazine mixture and fill about half an inch of test tube with it.
o Add 3-Sml of sugar solution (original solution) to the test tube. Mix thoroughly and place it in a boiling water bath. Note the appearance of yellow crystalline precipitate in the test tube. Remove and allow the test tube to cool slowly. Do not cool the test tube under tap water. Examine the crystals under the microscope and make a drawing. Draw only what you see. '
Osazones of glucose are formed in 10-15 minutes whereas those of disaccharides take upto 45 minutes. Sucrose does not react with phenylhydrazine to form crystalline compounds called osazones.
SUGAR I OSAZONE II SHAPE I
Glucose Glucosazone Needle shaped.
Fructose Fructosazone Needle shaped.
Galactose Galactosazone Fluffy ball shaped.
Lactose Lactosazone Fluffy ball shaped.
Maltose Maltosazone Sunflower shaped.
SPECIAL REACTIONS GIVEN BY THE INDIVIDUAL SUGARS
TEST FOR FRUCTOSE ( FREE OR COMBINED):
SELIWANOFF'S TEST:
Carbohydrate Biochemistry Tests
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