a. Shinoda Test(Magnesium Hydrochloride reduction test): To the test solution add few fragments of Magnesium ribbon add concentrated hydrochloric acid drop wise, pink scarlet, crimson red or occasionally green to blue colour appears after few minutes.
b. Zinc Hydrochloride reduction Test: To the test solution add a mixture of zinc dust and concentrated hydrochloric acid. It gives red colour after few minutes.
c. Alkaline Reagent Test: To the test solution add a few drops of sodium hydroxide solution; formation of an intense yellow colour which turns to colourless on addition of few drops of diluted acid indicates presence of flavonoids.
3.6.4 Test for Proteins and Amino acids
→ Millon’s Test: Test with 2ml of millons reagent (Mercuric nitrate in nitric acid containing traces of nitrous acid), White precipitate appears, which turns red upon gentle heating.
→ Ninhydrin Test: Amino acids and Proteins when boiled with 0.2% solution of Ninhydrin (Indane-1, 2, 3-trione hydrate), Violet colour appears.
3.6.5 Test for sterols and triterpenoids
§ Libermann-Butchard Test: Extract treated with few drops of acetic anhydride, boil and cool, concentrated sulphuric acid is added from the sides of the test tube, shows a brown ring at the junction of two layers and upper layer turns green which shows the presence of triterpenoids.
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