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Auramine O Chemical Structure

Home » Speciality Dyes and Biological Stains » Auramine O

What is Auramine O?

Auramine O is an aniline dye and is obtained by combining 4,4′-carbonimidoylbis(N,N-dimethylaniline) with one molar equivalent of hydrogen chloride. It is a diarylmethane dye and functions as both a fluorochrome and a histology stain.

Macsen Laboratories is the leading manufacturer and supplier of Auramine O with ISO certification.
Name of Product Auramine O
IUPAC Name 4-[4-(dimethylamino)benzenecarboximidoyl]-N,N-dimethylaniline;hydrochloride
Synonyms Auramine hydrochloride; Basic yellow 2; Pyocatanium aureum; Aizen auramine; Pyoktanin yellow; Canary yellow, pyoktanin; Auramin; Benzophenoneidum; Calcozine Yellow OX
CAS No 2465-27-2
Molecular Formula C17H21N3.HCl
Molecular Weight 303.8 g/mol
Color Index No 41000
Pubchem CID 17170
Pubchem SID 475523901


SR. No Criteria Limit/Specification
1 Appearance (form) Solid Powder or Flakes
2 Appearance (Color) Yellow
3 Melting Point >250 °C (dec)
4 Solubility 10 mg/ml in Water
60 mg/ml in Ethylene glycol methyl ether
20 mg/ml in Ethanol
5 Solubility (Color) Clear to hazy, Yellow to very deep yellow
6 Storage Room Temperature


  • In biology, Auramine O is used in combination with Rhodamine B as auramine-rhodamine stain to stain acid-fast organisms, e.g. Mycobacterium, where it forms a complex with the mycolic acid found in its cell wall.
  • It can be utilized in the dying of acrylic fibres, silk, and cotton, as well as leather, paper, hemp, and viscose.
  • It can also be used in direct printing and blotch discharge printing of tannin-mordant-dyed cotton, as well as in the production of color lakes and inks.
  • It is also possible to make a fluorescent variant of the Schiff reagent by using Auramine O.
  • It also has antiseptic properties and can be used for that purpose.


Q. What fluorescence is emitted by Auramine O?

When exposed to blue light (450–500 nm), Auramine O becomes excited and emits light in the range of around 500 nm to 700 nm (green–yellow–red).

Q. What does Auramine O stain?

Auramine O stain is utilized for the direct detection of mycobacteria in clinical specimens. It binds to mycolic acids and emits light when exposed to ultraviolet light. Acid-fast organisms (mycobacteria) thus appear yellow or orange in the UV light.


Biological Stains | Classification, Examples & Uses

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