Indigo carmine

• Indigo carmine
• Indigotine
• Indigotine -5, 5' -disulfonic acid disodium salt
• Acid Blue 74
• E 132
• C. I. 73015

Dark blue powder

Fixed

Sparingly soluble in water (10 g · l-1 ) and ethanol (1 g · l -1)

2000 mg · kg -1 ( LD50, rat, oral)

Template: Infobox chemical / molecular formula search available

Indigo carmine, also indigotin I, is a water soluble, blue indigo dye.

Chemical Properties

Indigotine is soluble in water (10 g / l at 25 ° C, with a pH of about 5.3 ). The UV / visible absorption spectrum shows a maximum in water at 608 to 612 nm

Use

It is used as pH indicator. Above a pH of 13 it is yellow, blue is below 11.4. Furthermore, it is used as a redox indicator which turns yellow at a reaction. It is also used to display dissolved ozone. In this case, its transformation into isatin -5- sulfonic acid is used, but also occurs with hyperoxides. Indigotin is used for coloring of soft drinks, liqueurs, sweets, ice cream, pasta and sugar-coated tablets. It is approved as a food additive E 132 and is as blue food dye or in combination with yellow dyes such as quinoline yellow ( E104 ) for green color ( see green paint) used. Aqueous solutions Indikarmin fade especially under the influence of light. Indigo carmine is very sensitive to light and oxidants.

Medically, it was formerly used for kidney function test.

Indigotin is considered safe, in longer feeding studies, however, indications have emerged that may arise nitrosamines from other foods in the presence of nitrite.