Indigo carmine

Indigo carmine

Names
IUPAC name 3,3′-dioxo-2,2′-bisindolyden-5,5′-disulfonic acid disodium salt
Other names indigotine 5,5′-indigodisulfonic acid sodium salt Brilliant Indigo4 G C.I. Acid Blue 74 C.I. 73015 Food Blue 1 C Blue 2 Sicovit Indigotin 85E 132.
Identifiers
CAS Number	860-22-0 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:31695 N
ChemSpider	4447431 Y
ECHA InfoCard	100.011.572
E number	E132 (colours)
PubChem	5284351
UNII	D3741U8K7L Y
InChI InChI=1S/C16H10N2O8S2.2Na/c19-15-9-5-7(27(21,22)23)1-3-11(9)17-13(15)14-16(20)10-6-8(28(24,25)26)2-4-12(10)18-14;;/h1-6,17-18H,(H,21,22,23)(H,24,25,26);;/q;2*+1/p-2/b14-13+;; Y Key: KHLVKKOJDHCJMG-QDBORUFSSA-L Y InChI=1/C16H10N2O8S2.2Na/c19-15-9-5-7(27(21,22)23)1-3-11(9)17-13(15)14-16(20)10-6-8(28(24,25)26)2-4-12(10)18-14;;/h1-6,17-18H,(H,21,22,23)(H,24,25,26);;/q;2*+1/p-2/b14-13+;; Key: KHLVKKOJDHCJMG-AKPRSONXBD
SMILES [Na+].[Na+].[O-]S(=O)(=O)c3cc4C(=O)\C(=C2\C(=O)c1cc(ccc1N2)S([O-])(=O)=O)Nc4cc3
Properties
Chemical formula	C16H8N2Na2O8S2
Molar mass	466.36 g/mol
Appearance	purple solid
Melting point	>300 °C (572 °F)
Solubility in water	10 g/L (25 °C (77 °F))
Hazards
GHS pictograms
GHS signal word	Warning
GHS hazard statements	H302
R-phrases	R22
S-phrases	S22 S24/25
NFPA 704	0 1 0
Pharmacology
ATC code	V04CH02 (WHO)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Indigo carmine, or 5,5′-indigodisulfonic acid sodium salt, is an organic salt derived from indigo by sulfonation, which renders the compound soluble in water. It is approved for use as a food colorant in the U.S and E.U., It has the E number E132. It is also a pH indicator.

Indigo carmine in a 0.2% aqueous solution 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 through the conversion to isatin-5-sulfonic acid. This reaction has been shown not to be specific to ozone, however: it also detects superoxide, an important distinction in cell physiology. 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.