Nurul Nadzirah Roslan
Carbohydrate Chemistry Laboratory Report
Galactaric Acid Test
Galactaric acid test differentiates galactose containing sugars from other sugars,
can differentiate lactose and galactose by time and amount of precipitate
Five test tubes are labeled with the four known carbohydrate names or the
unknown number. 0.5 g carbohydrate is weighed into a heat resistant labeled
test tube. 1 mL DI H
O and followed by 1 mL concentrated nitric acid is added
into the carbohydrate. The test tubes is mixed and placed into a beaker with
water, boiling water bath in the hood. Tubes are leaved in water bath for 1.0 to
1.5 hours. The beaker is then carefully removed off from the plate. Allowed to
cool. Parafilm tubes and the tubes are kept in the beaker. The beaker is kept in
the hood until next week. Next week: observation of presence (or absence) of
white crystal as + or – result is recorded.
glucose, galactose, lactose, sucrose and unknown Y-319C
A positive result was the formation of white crystal, which was the result for
galactose, lactose and unknown Y-319C.
A negative result is solution with no precipitate formed which was the result for
glucose and sucrose.
Benedict’s Acid Test
Benedict’s test differentiates between reducing and non-reducing sugars.
11 heat resistant test tubes is used and labeled with the appropriate
carbohydrate tested. 2 mL Benedict’s reagent is added into each test tube. 0.2
mL of the 10% carbohydrate solution to the appropriate tube. Mixed well. Test