Flavonoids are a diverse group of phytonutrients found in many plants. To identify flavonoids, several qualitative tests can be performed, including:



1. Shinoda Test

  • Procedure: Add a small amount of powdered sample to ethanol and then add a few pieces of magnesium turnings. Add concentrated hydrochloric acid dropwise.
  • Observation: The appearance of a pink, red, or orange color indicates the presence of flavonoids.

2. Ferric Chloride Test

  • Procedure: Add a few drops of 1% ferric chloride solution to the sample extract.
  • Observation: Formation of a green, blue, or black color suggests the presence of phenolic compounds, including flavonoids.

3. Lead Acetate Test

  • Procedure: Add a few drops of 10% lead acetate solution to the extract.
  • Observation: Formation of a yellow precipitate indicates the presence of flavonoids.

4. Alkaline Reagent Test

  • Procedure: Add a few drops of 10% sodium hydroxide to the sample extract.
  • Observation: Formation of an intense yellow color, which becomes colorless upon the addition of dilute acid, is indicative of flavonoids.

5. Zinc-Hydrochloric Acid Reduction Test

  • Procedure: To the extract, add zinc dust and a few drops of concentrated hydrochloric acid.
  • Observation: A red color indicates the presence of flavonoids.

These tests are useful for the preliminary identification of flavonoids. For confirmation and quantification, advanced techniques like UV-Vis spectroscopy, high-performance liquid chromatography (HPLC), or mass spectrometry are recommended.