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The cut surface of an apple stained with iodine, indicating a starch level of 4–5. The iodine–starch test is a chemical reaction that is used to test for the presence of starch or for iodine. The combination of starch and iodine is intensely blue-black. [1] [2] The interaction between starch and the triiodide anion (I − 3) is the basis ...
Sodium thiosulfate is used to reduce iodine back to iodide before the iodine can complex with the starch to form the characteristic blue-black color. Iodine is generated: 2 I − + S 2 O 2− 8 → I 2 + 2 SO 2− 4. And is then removed: I 2 + 2 S 2 O 2− 3 → 2 I − + S 4 O 2− 6. Once all the thiosulfate is consumed the iodine may form a ...
In mycology a tissue or feature is said to be amyloid if it has a positive amyloid reaction when subjected to a crude chemical test using iodine as an ingredient of either Melzer's reagent or Lugol's solution, producing a blue to blue-black staining.
The Minor test (also known as Minor's test, the starch–iodine test, and the iodine–starch test), described by Victor Minor in 1928, [1] is a qualitative medical test that is used to evaluate sudomotor function (perspiration or sweating).
In an iodometric titration, a starch solution is used as an indicator since it can absorb the I 2 that is released, visually indicating a positive iodine-starch test with a deep blue hue. This absorption will cause the solution to change its colour from deep blue to light yellow when titrated with standardized thiosulfate solution.
This solution is used as an indicator test for the presence of starches in organic compounds, [18] with which it reacts by turning a dark-blue/black. Elemental iodine solutions like Lugol's will stain starches due to iodine's interaction with the coil structure of the polysaccharide. Starches include the plant starches amylose and amylopectin ...
It is advised to check the references for photos of reaction results. [1] Reagent testers might show the colour of the desired substance while not showing a different colour for a more dangerous additive. [2]
This is an accepted version of this page This is the latest accepted revision, reviewed on 10 February 2025. This article is about the chemical element. For other uses, see Iodine (disambiguation). Chemical element with atomic number 53 (I) Iodine, 53 I Iodine Pronunciation / ˈ aɪ ə d aɪ n, - d ɪ n, - d iː n / (EYE -ə-dyne, -din, -deen) Appearance lustrous metallic gray solid ...