Indigo carmine
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| Names | |
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| IUPAC name
3,3'-dioxo-2,2'-bis-indolyden-5,5'-disulfonic acid disodium salt
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| Other names
indigotine; 5,5'-indigodisulfonic acid sodium salt
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| Identifiers | |
860-22-0  |
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| ChEBI | CHEBI:31695  |
| ChemSpider | 4447431 |
| Jmol 3D model | Interactive image |
| PubChem | 5284351 |
| UNII | D3741U8K7L |
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| Properties | |
| C16H8N2Na2O8S2 | |
| Molar mass | 466.36 g/mol |
| Appearance | purple solid |
| Melting point | >300 °C (572 °F) |
| 10 g/L (25 °C (77 °F)) | |
| Vapor pressure | {{{value}}} |
| Pharmacology | |
| ATC code | V04 |
| Vapor pressure | {{{value}}} |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 verify (what is ?) |
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| Infobox references | |
Indigo carmine, or 5,5'-indigodisulfonic acid sodium salt, also known as indigotine or FD&C Blue #2, is a pH indicator with the chemical formula C16H8N2Na2O8S2. It is approved for use as a food colorant in the United States[1] and in Europe.[2] and has the E number E132.
Contents
Uses
| Indigo Carmine (pH indicator) | ||
| below pH 11.4 | above pH 13.0 | |
| 11.4 | ⇌ | 13.0 |
Indigo carmine is commonly used as a pH indicator, often in a 0.2% aqueous solution. It is blue at pH 11.4 and yellow at 13.0. Indigo carmine is also a redox indicator, turning yellow upon reduction. Another use is as a dissolved ozone indicator[3] through the conversion to isatin-5-sulfonic acid.[3] This reaction has been shown not to be specific to ozone, however: it also detects superoxide, an important distinction in cell physiology.[4] It is also used as a dye in the manufacturing of capsules.
In obstetric surgery, indigo carmine solutions are sometimes employed to detect amniotic fluid leaks. In urologic surgery, intravenous injection of indigo carmine is often used to highlight portions of the urinary tract. The dye is filtered rapidly by the kidneys from the blood, and colors the urine blue. This enables structures of the urinary tract to be seen in the surgical field, and demonstrate if there is a leak. However, the dye can cause a potentially dangerous increase in blood pressure in some cases.[5]
Health concerns
Indigo carmine is harmful to the respiratory tract if inhaled. It is also an irritant to the skin and eyes. Proper laboratory cautions (lab coat, gloves, goggles) are advised.
See also
References
- ↑ Summary of Color Additives for Use in United States in Foods, Drugs, Cosmetics, and Medical Devices, United States Food and Drug Administration
- ↑ Current EU approved additives and their E Numbers, Food Standards Agency, 26 November 2010
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