BIOCHEMISTRY - Main Regulators and Biological Fluids of the Human Body - 2016

2. HORMONES

2.12. Practical Section. Study of Qualitative Reactions for Hormones

2.12.3. Qualitative Reactions for Thyroid Hormones

The primary hormone produced by The Thyroid Gland is thyroxine; triiodothyronine and diiodothyronine also exhibit hormonal activity.

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Experiment 6. Detection of Iodothyronines

The detection method for iodothyronines is based on the Cleavage of hydriodic acid during the acid Hydrolysis of THYROID Hormones (iodothyronines); when hydriodic acid reacts with potassium iodate, free iodine is released, which produces a crimson-violet color in chloroform.

Place a few crystals of L-thyroxine into a test tube, add 10 drops of concentrated nitric acid (HNO3), and heat for 3–5 minutes in a boiling Water bath. Then add 20 drops of a 1% potassium iodate (KIO3) solution. Mix the Contents of the test tube and let it cool. Afterward, add 15 drops of chloroform, shake vigorously, allow the layers to separate, and observe the characteristic coloration of the chloroform layer.

Record your observations in the report. Conclude which Structural Features of thyroxine are responsible for this chemical reaction.



Last update: 06/08/2026

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