M9140 Sigma-Aldrich

Methylene blue

certified by the Biological Stain Commission

Synonym: 3,7-bis(Dimethylamino)phenazathionium chloride, Basic Blue 9, Tetramethylthionine chloride

  • CAS Number 122965-43-9

  • Empirical Formula (Hill Notation) C16H18ClN3S · xH2O

  • Molecular Weight 319.85 (anhydrous basis)

  •  Colour Index Number 52015

  •  Beilstein/REAXYS Number 3599847

  •  EC Number 200-515-2

  •  MDL number MFCD00150006

  •  PubChem Substance ID 24897317

  •  NACRES NA.47



Related Categories Base Ingredients for Media, Cell Biology, Certified Stains & Dyes, Core Bioreagents, Hematology and Histology,
Quality Level   200
grade   certified by the Biological Stain Commission
form   powder
composition   Dye content, ≥82%
application(s)   hematology: suitable
  histology: suitable
solubility   H2O: 4mg/4ml
Featured Industry   Diagnostic Assay Manufacturing
storage temp.   room temp
SMILES string   CN(C)C1=CC=C2C(SC(C3=N2)=CC(C=C3)=[N+](C)C)=C1.[H]O[H].[Cl-]
InChI   1S/C16H18N3S.ClH.H2O/c1-18(2)11-5-7-13-15(9-11)20-16-10-12(19(3)4)6-8-14(16)17-13;;/h5-10H,1-4H3;1H;1H2/q+1;;/p-1
Gene Information   human ... CYP1A2(1544), GSR(2936)


General description

Methylene blue is a compound that occurs as crystals or crystalline powder, having a bronze-like luster. It is soluble in water, chloroform and partially soluble in alcohol. It is a photoactive dye, which is a member of phenothiazine family.


Methylene blue has been used:
• to stain vaginal cells
• for the preparation of protein aqueous ink
• to evaluate cell survival by staining


25, 100 g in glass bottle

Biochem/physiol Actions

Methylene blue is used as a bacteriologic stain or dye and indicator. It mediates the inactivation of enveloped viruses in plasma, when exposed to visible light. It is an inhibitor of nitric oxide synthase and guanylate cyclase. It also plays a key role in medicine as an antimalarial agent, reducing agent in methemoglobinemia and inducer of apoptosis in cancer cells.


Certified for use in Mallory′s phloxine-methylene blue stain; Levine & Black stain for bacteria in milk; Wright stain for blood smears.

Safety & Documentation

Safety Information

GHS07  GHS07
Signal word 
Hazard statements 
Precautionary statements 
Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable


Certificate of Analysis (COA)

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Certificate of Origin (COO)

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Frequently Asked Questions

Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
What is the solubility of Methylene blue, Product M9140?
The product is soluble in water at 50 mg/mL, EGME at 60 mg/mL and ethanol at 70 mg/mL. EGME is an abbreviation for ethylene glycol monomethyl ether, also known as 2-methoxyethanol or methyl cellosolve.
How canMethylene blue, Product M9140, be used?
Probably its most important application is as an in vitro diagnostic bacteriology, cytology, hematology, and histology stain. Methylene Blue serves as a precursor to the Methylene Azures and as a component of the various Ramanowsky-type blood stains (Wright, Leishman, Giemsa and others). While pure Methylene Blue is not a good nuclear stain, it readily undergoes oxidative demethylation to form the various Methylene Azures, which are good nuclear stains.
How is dye content determined for Methylene blue, Product M9140?
Dye content is determined spectrophotometrically by noting the dye's absorbance peak, which is typically near 665 nm, or by calculating the ratio of the absorbances at 650 nm over 680 nm. (The dye exhibits smaller peaks at approximately 292 and 246 nm).
How do I find price and availability?
There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote. USA customers: 1-800-325-3010 or view local office numbers.
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
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