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In this article we will discuss about the tests for detection of tannins in plants.
Tannins are a heterogeneous group of organic compounds found in plants. They are commonly present in unripe fruits — guava, banana and leaves of tea etc. These are water-soluble compounds. The metabolic significance of these compounds are not clearly known but they play a significant role in disease resistance in certain plants.
Requirements for Detection of Tannins:
(a) Preparation of Sample Solution:
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Tannins can be easily extracted by boiling the plant materials in water.
The extract is filtered and following tests are performed:
(b) Reagents:
1. Ferric chloride (5%) solution.
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2. Dilute NH4OH solution.
3. Potassium ferricyanide solution (5%).
4. Iodine solution (1%).
5. Dilute HNO3 solution.
6. Acetic acid.
7. Potassium dichromate solution (5%).
8. Silver nitrate solution (10%).
Tests for Detection of Tannins:
Experiment:
Test 1:
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A few drops of 5% Ferric Chloride solution is added to the extract of tannin.
Test 2:
To a small quantity of extract dilute NH4OH is added, followed by addition of potassium ferricyanide solution.
Test 3:
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A few drops of Iodine solution are added to the tannin extract
Test 4:
A few drops of dilute HN03 are added to the tannin extract to the tannin extract.
Test 5:
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A few drops of acetic acid are added to the extract.
Test 6:
A few drops of Potassium dichromate are added to the extract.
Test 7:
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In a test tube, tannin extract is taken and to it a drop of dil. NH4OH is added. Then excess of 10% AgNO3 soln. is then excess of 10% AgNO3 soln. is added. The mixture is placed in a added. The mixture is placed in a
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Observation:
A deep blue-black colour is formed
The solution turns red in colour
A transited red colour is formed
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The solution turns dark red in colour
The solution produces red ppt.
Initially a white precipitate is formed. Then a dark silver mirror is formed on the wall of the test tube.
Inference:
Presence of Tanni.
Presence of Tanni.
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Presence of Tanni.
Presence of Tanni.
Presence of Tanni.
Presence of Tanni.
Presence of Tanni.
