Patent Blue V structure

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What is Patent Blue V (Acid Blue 3)

Patent Blue V or Acid Blue 3 is a synthetic triphenylmethane dye. It occurs as dark blue powder or granules. It is principally the calcium or sodium salt of 2-[4-[alpha-(4-diethyl-aminophenyl)-5-hydroxy-2,4-disulfonatophenylmethylidene]-2,5-cyclohexadien-1-ylidene] diethylammonium hydroxide inner salt, and subsidiary colouring matters. It is also called Food Blue 5, Sulphan Blue, Acid Blue 3, L-Blau 3, C-Blau 20, Patentblau V, or Sky Blue C.I. 42051. It is used as a food additive in certain jelly sweets and gelatin desserts in Europe.

Macsen Laboratories is the manufacturer and supplier of high-quality Patent Blue V.
Name of Product Patent Blue V
IUPAC Name calcium;4-[[4-(diethylamino)phenyl]-(4-diethylazaniumylidenecyclohexa-2,5-dien-1-ylidene)methyl]-6-hydroxybenzene-1,3-disulfonate
Synonyms Acid Blue 3, C.I. Food Blue 5, Carmine Blue V, Acidal Carmine V, Merantine Blue V
CAS No 3536-49-0
Molecular Formula C54H62CaN4O14S4
Molecular Weight 1159.4 g/mol
Pubchem CID 77073
Pubchem SID 463751340

Chemical Properties

SR. No Criteria Limit/Specification
1 Appearance (Color) Dark Blue
2 Appearance (Form) Powder or Granules
3 UV Spectra Maximum in water at 638 nm at pH 5
4 Total Dye Content (percent by mass) ≥85.0%
5 Loss on Drying at 135°C <45%
6 Water Insoluble matter >0.2%
7 Assay ≥97.0% (HPLC)
8 Uses Food additive, Cosmetic colorant, Dye


  • Patent Blue V is a dye used in lymphangiography and sentinel node biopsy in medicine to colour lymph vessels.
  • It is also used as a stain in dental disclosing tablets to reveal dental plaque on teeth.
  • It is useful as a pH indicator for the range 0.8–3.0.
  • It is usable as a reversible redox indicator in some analytical methods.

Side effects

Rash, pruritus, erythema, urticaria, angioedema (such as facial oedema or laryngeal oedema), bronchospasm, tachycardia, reduced blood pressure, and circulatory collapse are the most commonly reported consequences in the setting of a hypersensitive reaction associated with the excessive dosage of Patent Blue V.


Q. What is the use of Patent Blue V in pharmaceuticals?

Patent Blue V is a sterile injectable dye solution. It is a triphenylmethane dye that is used to reveal vessels in order to improve the imaging of certain vessels in your body.

Q. Is Patent Blue the same as Methylene Blue?

Both Patent Blue and Methylene Blue are used as diagnostic agents for the detection of the sentinel lymph node in breast cancer patients. But in contrast to Patent Blue, Methylene Blue is more widely available and much more cost-effective. Also, Patent Blue poses a greater risk of anaphylaxis and hypersensitivity reactions, thus methylene blue is the preferred choice of agent.


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