VPB 112: General Veterinary Biochemistry (1+1)

LEAD ACETATE TEST

• This test is specific for sulphur containing amino acids (Cysteine, Cystine and Methionine).

Principle

• On boiling the sulphur containing amino acids, the sulphur is split off from these amino acids as metallic sulphides (K₂S or Na₂S).
• By the addition of lead acetate, they are oxidized to black colored lead sulphides.

Procedure

• To 2 ml of the test solution add 2 ml of 10% NaOH and boil for a minute.
• Add a drop of lead acetate solution.
• A brown or a black precipitate is formed.