Indigo carmine
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| General | |||||||||||||||||||
| Surname | Indigo carmine | ||||||||||||||||||
| other names |
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| Molecular formula | C 16 H 8 N 2 Na 2 O 8 S 2 | ||||||||||||||||||
| Brief description |
dark blue powder |
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| properties | |||||||||||||||||||
| Molar mass | 466.36 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| solubility |
sparingly soluble in water (10 g l −1 ) and ethanol (1 g l −1 ) |
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| Toxicological data | |||||||||||||||||||
| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Indigo carmine , also called indigotine I , is a water-soluble, blue indigoid acid dye .
Chemical properties
Indigotine is water-soluble (10 g / l at 25 ° C, with a pH of around 5.3). The UV / VIS absorption spectrum shows a maximum in water at 608-612 nm.
use
It is used as a pH indicator . Above pH 13 it is yellow, below 11.4 it is blue. It is also used as a redox indicator, which turns yellow upon reaction. It is also used to display dissolved ozone . Its conversion into isatin-5-sulfonic acid is used, which, however, also occurs with hyperoxides .
Indigotine is used to color non-alcoholic beverages, liqueurs , confectionery, ice cream , pasta, coated tablets and tablets as well as medicines. It is approved as a food additive E 132 and is used as a blue food coloring or in combination with yellow coloring such as quinoline yellow (E104) for green coloring (see green varnish) . Aqueous indicarmine solutions fade, especially when exposed to light. Indigo carmine is very sensitive to light and oxidants.
Medically, it was previously used to test kidney function.
Indigotine is considered to be harmless, but lengthy feeding studies have shown that nitrosamines can be formed from other foods in the presence of nitrite .
Web links
- Zusatzstoffe-Online.de: Indigo carmine
- Indigo carmine at chemistryworld.de
- Periodic Table of Videos - Video from a demonstration experiment at Nottingham University
Individual evidence
- ↑ Entry on E 132: Indigotine, Indigo carmine in the European database for food additives, accessed on June 16, 2020.
- ↑ a b c Entry on indigo carmine. In: Römpp Online . Georg Thieme Verlag, accessed on March 4, 2014.
- ↑ a b Data sheet Indigo carmine at AlfaAesar, accessed on December 7, 2019 ( PDF )(JavaScript required) .
- ↑ Sometimes you can also find the term indigotine for indigo carmine . However, indigotine is an alternative name for indigo .