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Indigo Carmine USP (860-22-0)

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Indigo Carmine USP

What is Indigo Carmine ?

Indigo Carmine or Indigotindisulfonate Sodium is an organic sodium salt formed via formal condensation of indigo carmine (acid form) with two equivalents of sodium hydroxide. It occurs as Indigo to dark blue powder, soluble in water and ethanol and practically insoluble in most other organic solvents. It is approved for use as a food dye in the United States and the EU and has the E number E132. It is an indicator at pH 11.5-14.

It belongs to a class of drugs called Miscellaneous Diagnostic Dyes and is used for the intraoperative detection of suspected ureteral injuries throughout abdominal and pelvic surgery. It is also a traditional drug used as an individual agent for kidney function tests.

Macsen Labs is a US FDA, EUGMP – WC, WHO GMP, ISO Certified Manufacturer and Supplier of high-quality Indigo carmine USP.
Name of Product Indigo Carmine
Pharmacopoeial Name Indigo Carmine USP
IUPAC Name disodium;2-(3-hydroxy-5-sulfonato-1H-indol-2-yl)-3-oxoindole-5-sulfonate
Synonyms Indigotine; 5,5′-indigodisulfonic acid sodium salt; C.I. Acid Blue 74; C.I. Food Blue 1; Indigotindisulfonate sodium; Amacid Brilliant Blue; índigo carmim; Indaco carminio; Carmin indigo
CAS No 860-22-0
Molecular Formula C16H8N2Na2O8S2
Molecular Weight 466.4 g/mol
Pubchem CID 2723854
Pubchem SID 462768915
WC Available soon
US-DMF Available soon


SR. No Criteria Limit/Specification
1 Appearance and Odor Dusky, purplish-blue powder or blue granules having a coppery luster. Its solutions have a blue or bluish purple color.
2 Solubility Slightly soluble in water and in alcohol; practically insoluble in most other organic solvents (i.e. chloroform).
Test A
For Sodium Meets the Requirement - A dense precipitate is formed. Sodium compound impart an intense yellow color to a non-luminous flame.
For Sulfate Meets the Requirement - Solution of sulfates yield a white precipitate that is insoluble in hydrochloric acid and in nitric acid.
Test-B Meets the Requirement - Changes the color to bluish violet, and further dilution with water restores the original color
Test-C Meets the Requirement - Changes the color to yellow or olive-brown
Test-D Meets the Requirement - Produces a blue precipitate
4 Assay By UV-Vis (On Dried Basis) NLT 96.0% and NMT 102.00 %
Sulfur Content

13.0% - 14.0% on the dried basis
Arsenic (Bv ICP-OES)
Lead (Bv ICP-OES)

NMT 8ppm
NMT l0 ppm (0.001%)
Loss on Drying (LOD)
Water-Insoluble Substances

NMT 5.0%
The weight of the residue does not exceed 5 mg (0.5%)
8 Additional Tests (Microbiology)
Bacterial Endotoxin Test

NMT 2.5 Endotoxin Units/mg
Total aerobic microbial count (TAMC)
Total combined yeasts and molds counts (TYMC)
NMT 1000 cfu/s
NMT 100cfu/g
a. E.coli
b. Salmonella
c. Staphylococcus aureus
d. Pseudomonas aeruginosa
e. Candida albicans

Should be absent
Should be absent
Should be absent
Should be absent
Should be absent


  • Indigo Carmine is blue at pH 11.4 and yellow at pH 13.0 in a 0.2% aqueous solution. It is a redox indicator that becomes yellow when reduced.
  • Through the conversion to isatin-5-sulfonic acid, it can also be used as a dissolved ozone indicator.
  • It is also utilised in the production of capsules as a dye.
  • Indigo carmine intravenous injections are widely used in urologic surgery to highlight areas of the urinary system. The dye is swiftly filtered from the blood by the kidneys, turning the urine blue. This enables surgeons to examine the architecture of the urinary system in the operating room and detect if a leak exists.
  • Indigo Carmine solutions are occasionally used in obstetric surgery to detect amniotic fluid leaking.
  • Indigo carmine stain, employed at a concentration of about 0.2 %, is beneficial as a screening approach for diagnosing minute lesions and distinguishing between benign and malignant lesions.
  • It also has a role as a food colouring agent.

Side effects

Indigo Carmine can cause some serious side effects which include:

  • Hives, Rashes & Pruritis
  • Difficulty in breathing
  • Swelling of face, lips, tongue, or throat
  • May include a mild rise in blood pressure
  • Nausea
  • Vomiting
  • Bronchoconstriction may occur occasionally

Also, It may interact with other drugs, so it is necessary to take it with a doctor’s prescription.


Q. Where to buy Indigo Carmine?

Macsen Drugs, a unit of Macsen labs is a WHO-GMP, US-FDA and ISO-certified manufacturer and supplier of high-quality Indigo Carmine.

Q. Is Indigo carmine the same as Methylene blue?

When excited by the white light, Methylene Blue, unlike Indigo Carmine, is taken up by the cells and causes cellular DNA damage in vitro by generating singlet oxygen. Indigo carmine, on the other hand, seems to be photo-stable and has limited ability to harm genetic codes in vitro. The degree of DNA damage (especially oxidative DNA damage) in oesophageal cells is enhanced following Methylene Blue, according to a recent clinical investigation.

Q. Is Indigo carmine FDA approved?

Indigo Carmine is not approved by FDA.

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