VPB 112: General Veterinary Biochemistry (1+1)

BENEDICT’S TEST

• It is the most popular test for identifying the sugar in urine. This test identifies a reducing sugar.

Principle

• Reducing sugar, when treated with Benedict’s reagent, tautomerize to form enediols.
• These enediols are unstable and decompose to yield a variety of products.
• These enediols convert the formed cuprous hydroxide, to a red precipitate of cuprous oxide.
• In this reaction, sodium citrate functions as a chelating agent.

Procedure

• To 2.5 mL of Benedict’s reagent add 4 drops of the test solution and boil the mixture.
• Reducing sugars form a precipitate, which may be green, yellow, orange or brick red.
• The color of the solution depends on the concentration of the sugar present in it.